The Musical Fallout of Political Activism: Government Investigations of Musicians in the United States, 1930-1960 (open access)

The Musical Fallout of Political Activism: Government Investigations of Musicians in the United States, 1930-1960

Government investigations into the motion picture industry are well-documented, as is the widespread blacklisting that was concurrent. Not nearly so well documented are the many investigations of musicians and musical organizations which occurred during this same period. The degree to which various musicians and musical organizations were investigated varied considerably. Some warranted only passing mention, while others were rigorously questioned in formal Congressional hearings. Hanns Eisler was deported as a result of the House Committee on Un-American Activities' (HUAC) investigation into his background and activities in the United States. Leonard Bernstein, Marc Blitzstein, and Aaron Copland are but a few of the prominent composers investigated by the government for their involvement in leftist organizations. The Symphony of the Air was denied visas for a Near East tour after several orchestra members were implicated as Communists. Members of musicians' unions in New York and Los Angeles were called before HUAC hearings because of alleged infiltration by Communists into their ranks. The Metropolitan Music School of New York, led by its president-emeritus, the composer Wallingford Riegger, was the subject of a two day congressional hearing in New York City. There is no way to measure either quantitatively or qualitatively the effect of …
Date: August 1993
Creator: McCall, Sarah B.
System: The UNT Digital Library
Circumfusion: a Composition for Real-Time Computer Music Spatialization System (open access)

Circumfusion: a Composition for Real-Time Computer Music Spatialization System

Two of the leading methodologies for spatializing audio over multiple channels include non-real-time multi-track tape and variations of real-time systems that often involve complex configurations of hardware. Of the latter, composers relying on MIDI as a control source have used pairs of sound modules, effects units and automation capable mixers to achieve spatialization over four loudspeakers. These systems typically employ intensity panning, Doppler shifts and reverberation. The present research details the development of a compact spatialization system using a MAX patch controlling a Kurzweil K2500 sampler. This system supports real-time diffusion of up to six simultaneous sound files over eight loudspeakers while incorporating intensity panning, Doppler shifts, delays and filtering. The MAX patch allows composers to choose from several automatic sound spatialization trajectories or to use the mouse to draw and store their own trajectories for later playback. The piece, Circumfusion, is an eighteen-minute composition of electroacoustic music utilizing this spatialization system.
Date: August 1998
Creator: Morgan, Christopher R. (Christopher Robert)
System: The UNT Digital Library
Selected Structural Elements and Aspects of Performance in Bagatelles (1971) and Konstellationen (1972) by Krystyna Moszumanska-Nazar, with Three Recitals of Works by Beethoven, Brahms, Chopin, Liszt, Messiaen, Prokofieff, and Schumann (open access)

Selected Structural Elements and Aspects of Performance in Bagatelles (1971) and Konstellationen (1972) by Krystyna Moszumanska-Nazar, with Three Recitals of Works by Beethoven, Brahms, Chopin, Liszt, Messiaen, Prokofieff, and Schumann

This dissertation primarily concerns selected structural elements in Bagatelles and Konstellationen. These are pitch/interval, rhythm/meter in Bagatelles, the formal design and its relations with dynamics and texture in Konstellationen, as well as the usage of indeterminacy. There are also selected aspects of performance in regard to extended technique, pedaling, and certain dynamic control problems related to two works in question. Chapter one introduces the historical background of Polish music and the emergence of Poland as one of the leading forces in contemporary music. It also provides the musical background of Moszumanska-Nazar, as well as the stylistic features and representative works in her three compositional periods. Personal interviews and correspondence with the composer provide additional biographical and stylistic insight for this chapter. Chapter two focuses on the aspects of structural procedure. In Bagatelles, the structural elements are: organized pitch sets, the dominance of linear interval, scale pattern, dissonant intervals, as well as the rhythmic pattern and the various metric designs. Konstellationen present most interesting and unusual formal design in that the elements that delineate the form are dynamics, texture and certain pianistic devices, such as the ostinato, trills, abrupt high notes, irregular fast notes, and clusters. Chapter three addresses particularly the …
Date: August 1996
Creator: Long, Christina Ay-Chen
System: The UNT Digital Library
Contours (open access)

Contours

Contours is scored for full wind ensemble and percussion, and is approximately nine minutes in length. The title refers to the way melodic shape or contour is used to create unity and variety in the piece. Contours is a single-movement work containing three sections that are unified by thematic and harmonic materials. The melodic material is generated by three twelve-tone rows, which are then used in combination with freely composed material. The first and last sections are highly contrapuntal and rhythmically disjunct. Both sections share common rhythmic and melodic patterns. These sections are contrasted with a slower and more lyric middle section. This section is made of a series of episodes that create an overall A-B-A structure.
Date: August 1994
Creator: Hughes, Russell M., 1954-
System: The UNT Digital Library
I Never Saw Another Butterfly: A Composition for SATB Choir and Chamber Orchestra (open access)

I Never Saw Another Butterfly: A Composition for SATB Choir and Chamber Orchestra

...I never saw another butterfly... is a twelve movement chamber work scored for SATB choir, narrator, percussion I [vibraphone, and tomtoms (4)], percussion II [timpani (4), tam-tam, snare drum, and bass drum], guitar, violins I and II, viola, and cello and is based on the book of the same name. It contains a variety of compositional techniques, forms and genres.
Date: August 1997
Creator: Schneider, Gregory Alan
System: The UNT Digital Library
Music Preferences 1980 Versus 1989 and Their Relationship With Selected Environment and Listener Variables (open access)

Music Preferences 1980 Versus 1989 and Their Relationship With Selected Environment and Listener Variables

The purpose of this study was to determine differences between the same subjects' music preferences at the elementary and high school levels, and the relationship between these findings and the following variables: peer preferences, musical training, excerpt familiarity, grade, gender, and race.
Date: August 1994
Creator: Novak, Jennifer J. Doud
System: The UNT Digital Library
A Study of Idiomatic Piano Compositions During the Cultural Revolution in the People's Republic of China (open access)

A Study of Idiomatic Piano Compositions During the Cultural Revolution in the People's Republic of China

This study demonstrated that the piano, a typical Western instrument, became the Chinese composer's tool for expressing the sound ideals and tone qualities that are intrinsic to Chinese music. A new musical idiom was created in these piano compositions, an idiom that combined Western compositional techniques and traditionally-based Chinese ideals.
Date: August 1991
Creator: Fan-Long, Grace (Chun Grace)
System: The UNT Digital Library
The Trumpet in Selected Solo and Chamber Works of Paul Hindemith : Elements of Trumpet Technique and Their Relationship to the Gebrauchsmusik Concept, a Lecture Recital, Together with Three Recitals of Selected Works of J.N. Hummel, A. Jolivet, C. Chaynes, and Others (open access)

The Trumpet in Selected Solo and Chamber Works of Paul Hindemith : Elements of Trumpet Technique and Their Relationship to the Gebrauchsmusik Concept, a Lecture Recital, Together with Three Recitals of Selected Works of J.N. Hummel, A. Jolivet, C. Chaynes, and Others

The trumpet was one of the wind instruments Hindemith used frequently in his chamber music, and he employed it prominently in five works from 1925 to 1954. These works are the Sonate fur Trompete (1939), the Konzert fur Trompete in B und Fagott mit Streichorchester (1954), Drei Stucke (19251 the Septett fur Blasinstrumente (1949), and "Morgenmusik," from the collection Plöner Musiktag (1932). This study examines and compares Hindemith's writing for the trumpet in these selected works, noting features in his use of the instrument which determine the applicability of the works to the Gebrauchsmusik concept.
Date: August 1994
Creator: Bogard, Rick
System: The UNT Digital Library
The Function of Oral Tradition in Mary Lou's Mass by Mary Lou Williams (open access)

The Function of Oral Tradition in Mary Lou's Mass by Mary Lou Williams

The musical and spiritual life of Mary Lou Williams (1910 - 1981) came together in her later years in the writing of Mary Lou's Mass. Being both Roman Catholic and a jazz pianist and composer, it was inevitable that Williams would be the first jazz composer to write a setting of the mass. The degree of success resulting from the combination of jazz and the traditional forms of Western art music has always been controversial. Because of Williams's personal faith and aesthetics of music, however, she had little choice but to attempt the union of jazz and liturgical worship. After a biography of Williams, discussed in the context of her musical aesthetics, this thesis investigates the elements of conventional mass settings and oral tradition found in Mary Lou's Mass.
Date: August 1996
Creator: Fledderus, France
System: The UNT Digital Library
The Keyboard Percussion Trios of Toru Takemitsu and Toshi Ichiyanagi, a Lecture Recital, together with Three Recitals of Selected Works of Cahn, Maslanka, Miki, Miyoshi, Ptaszynska, Schultz, Wesley-Smith, and Others (open access)

The Keyboard Percussion Trios of Toru Takemitsu and Toshi Ichiyanagi, a Lecture Recital, together with Three Recitals of Selected Works of Cahn, Maslanka, Miki, Miyoshi, Ptaszynska, Schultz, Wesley-Smith, and Others

The purpose of this study is to examine the various signatures of compositional style as manifested in the keyboard percussion trios Rain Tree by Toru Takemitsu and Wind Trace by Toshi Ichiyanagi. Significant personal interaction between the aforementioned Japanese composers and American composer John Cage justifies an investigation of his influence on their compositional styles. Toru Takemitsu is currently one of the most prolific Japanese composers. In 1981, Takemitsu composed the percussion trio Rain Tree. Three years later (1984) the Japanese concert pianist Toshi Ichiyanagi composed Wind Trace using Rain Tree's identical instrumentation of marimba, vibraphone, and crotales. Rain Tree and Wind Trace are very similar in compositional style. Formally, both works are single-movement compositions employing rhythmic tension, harmonic dissonance, and visual imagery created by the use of polyrhythms, aleatory, nonfunctional harmony, and extra-musical references. This study investigates the Japanese philosophy of ma and its influence in Rain Tree and Wind Trace. Ma is the natural pause or interval between two or more phenomena occurring continuously. According to Takemitsu, ma is living space, more than actual space. Both compositions utilize space as an essential compositional technique to either connect compartmentalized activity or to complement melodic material. With the utmost respect …
Date: August 1995
Creator: Finnie, Jimmy W. (Jimmy Wayne)
System: The UNT Digital Library
Comparative Study of the Bel Canto Teaching Styles and their Effects on Vocal Agility (open access)

Comparative Study of the Bel Canto Teaching Styles and their Effects on Vocal Agility

This thesis examines the historical significance of the vocal methods employed from the middle of the seventeenth century to the beginning of the nineteenth century in what became known as the bel canto era. It provides further exploration into the pedagogical procedures of the bel canto technique through a study of the premier instructors and singers from this period. The resurgence of interest in this tradition is addressed along with its impact on current vocal pedagogy. The vital role that vocal agility played as one of its most distinguishing traits is the primary factor under investigation. A discussion of the bel canto teaching styles in relation to their approach to agility is a major point of inquiry. By maintaining a link between present artists and pedagogues and the old Italian school, it helps the singer understand the historical implications of vocal agility as an integral part of healthy vocal development.
Date: August 1996
Creator: Harper, Portia
System: The UNT Digital Library
Temporal Distortions: a Composition for Orchestra (open access)

Temporal Distortions: a Composition for Orchestra

Temporal Distortions is 18-20 minutes in length and is written for an orchestra including 2 flutes (2nd flute doubling on piccolo), 2 oboes, 2 Bb clarinets, 2 bassoons, 2 horns, 2 trumpets, 2 trombones, timpani, 3 percussionists playing tri-toms, vibraphone, snare/tenor drum, medium suspended cymbal, Glockenspiel, bass drum, and large tam-tam; and multiple string parts for violin I a & b, violin II a & b, viola a & b, cello and double bass. Temporal Distortions was inspired by the theoretical concept of "wormholes" in space, where matter is warped through distorted passages connecting distant and diverse parts of the universe. The work is in three sections, connected without break. The first section, Space, emerges as a wide, expansive musical area where themes and gestures are freely presented. Gradually, these materials come into phase with one another, building to a climax. A transition follows, leading into the middle section, Wormholes, where the materials are frequently and suddenly transformed into other temporal elements. The third section, Comets, was inspired by the collision of the comet Shoemaker-Levy 9 with the planet Jupiter in July of 1993. Driving, underlying rhythms propel the thematic material through a series of statements which split into more …
Date: August 1995
Creator: Frank, Robert J., 1961-
System: The UNT Digital Library
The School Fugue: Its Place in the Organ Repertoire of the French Symphonic School, a Lecture Recital, Together with Three Recitals of Selected Works of J.S. Bach, D. Buxtehude, C. Franck, P. Eben, F. Mendelssohn, R. Schumann, M. Reger and Others (open access)

The School Fugue: Its Place in the Organ Repertoire of the French Symphonic School, a Lecture Recital, Together with Three Recitals of Selected Works of J.S. Bach, D. Buxtehude, C. Franck, P. Eben, F. Mendelssohn, R. Schumann, M. Reger and Others

This study focuses on the central role which fugue d'ecole, as defined and taught by the post-revolutionary Conservatoire de Paris, played in re-establishing standards of excellence in organ composition and aiding the development of the French Symphonic Organ School. An examination of counterpoint and fugue treatises by Cherubini, Dubois, and Gedalge reveals the emergence of a specific school fugue form, intended for academic purposes only, as a means to instilling discipline and honing the technical skills required in all forms of musical composition.
Date: August 1994
Creator: Mulvey, Margaret N.
System: The UNT Digital Library
An Examination of the Percussion Writing in the Chamber Works of George Crumb, 1960-1980 with Three Recitals of Selected Works of Bergsma, Kurka, Miyoshi, Niimi, Takemitsu, and Others (open access)

An Examination of the Percussion Writing in the Chamber Works of George Crumb, 1960-1980 with Three Recitals of Selected Works of Bergsma, Kurka, Miyoshi, Niimi, Takemitsu, and Others

In this study, the unique style of percussion writing in the chamber works of George Crumb, written between 1960 and 1980, is examined. The principal aspects examined within this study include: the extended instrumental techniques, the use of percussion within the musical imagery, soloistic treatment, compositional and notational procedures, and specific performance problems pertaining to the chamber work Songs, Drones, and Refrains of Death.
Date: August 1993
Creator: LedBetter, Robert B.
System: The UNT Digital Library
Three Motivic Topics in Beethoven's Piano Quintet, Op. 16 (open access)

Three Motivic Topics in Beethoven's Piano Quintet, Op. 16

The first movement of the Piano Quintet, Op. 16 of Ludwig van Beethoven works out three significant motivic "topics": a chromatically filled-in second, appearing first as 5 - #5 - 6 (Bb - B - C in Eb major); the emphasis om the submediant, both as vi in Eb major and as the tonal region of C minor; and the melodic interval of the sixth, which, when inverted to become a descending third, determines the structure of tonal regions at crucial points in the movement. These three motivic topics are introduced in the opening measures of the piece and are subsequently unfolded throughout the movement; the focus of the thesis will be to trace the unfolding of these three topics.
Date: August 1995
Creator: Gratton, J. Brian (John Brian)
System: The UNT Digital Library
Mail Order Music: the Hinners Organ Company in the Dakotas, 1879-1936 (open access)

Mail Order Music: the Hinners Organ Company in the Dakotas, 1879-1936

Founded in 1879 by John L. Hinners, the Hinners Organ Company developed a number of stock models of small mechanical-action instruments that were advertised throughout the Midwest. Operating without outside salesmen, the company was one of the first to conduct all of its affairs by mail, including the financial arrangements, selection of the basic design, and custom alterations where required. Buyers first met a company representative when he arrived by train to set up the crated instrument that had been shipped ahead of him. Tracker organs with hand-operated bellows were easily repaired by local craftsmen, and were suited to an area that, for the most part, lacked electricity. In all, the company constructed nearly three thousand pipe organs during its sixty years of operation. Rapid decline of the firm began in the decade prior to 1936 during which the company sold fewer than one hundred instruments, and closed in that year when John's son Arthur found himself without sufficient financial resources to weather the lengthy depression. The studies of the original-condition Hinners organs in the Dakotas include extensive photographs and measurements, and provide an excellent cross section of the smaller instruments produced by the company. They are loud, excellently crafted, …
Date: August 1997
Creator: Alcorn-Oppedahl, Allison A. (Allison Ann)
System: The UNT Digital Library
Soloistic Writing for the Oboe in the Arias of Handel's Operas, with Three Recitals of Selected Works by Marcello, Strauss, Ravel, Bach, Handel, Saint-Saens and Others (open access)

Soloistic Writing for the Oboe in the Arias of Handel's Operas, with Three Recitals of Selected Works by Marcello, Strauss, Ravel, Bach, Handel, Saint-Saens and Others

Although long-neglected, the topic of Handel's operatic oeuvre has in recent years gained new currency. Of interest to oboists is the great amount of soloistic writing for the oboe in the arias of his operas which takes the form of obbligato solos. From this body of works approximately twenty operas contain soloistic writing for the oboe in conjunction with the voice. The rationale for the investigation of this topic is two-fold: first, to make oboists aware of the availability of this body of literature, and second, to explore the manner and extent to which Handel used the oboe as an obbligato instrument. Topics covered include the instrumental make-up of Handel's orchestra and a brief history of the obbligato aria beginning with the early trumpet arias. An examination of Handel's compositional technique precedes a detailed analysis of six examples of varying style. The conclusion considers the aesthetics of performing these pieces out of context in light of historical practice and perception.
Date: August 1996
Creator: Hiramoto, Stephen Anthony
System: The UNT Digital Library
An Interpretive Approach to Two Wind Partitas of Franz Vincent Krommer: Partita in F, Op. 57 (1808) and Partita in E-flat, Op. 79 (1810), A Lecture Recital : Together with Three Recitals of Selected Works of Stravinsky, Hanson, Martin Mailman, Holst and Walton (open access)

An Interpretive Approach to Two Wind Partitas of Franz Vincent Krommer: Partita in F, Op. 57 (1808) and Partita in E-flat, Op. 79 (1810), A Lecture Recital : Together with Three Recitals of Selected Works of Stravinsky, Hanson, Martin Mailman, Holst and Walton

An interpretive approach to performing two works by Franz Krommer for wind ensemble. Including a short history of Harmoniemusik, with origins, development, and chronology of the instruments and repertoire, the roles of "better-known" composers of Harmoniemusik, and its importance in both general music history and history of the wind band. An account of known biographical detail concerning Franz Krommer, his life, his musical involvement and career in Europe, and his place in music history. An overview of his compositions for wind groups other than the Harmoniemusik, including his symphonic music and concertos. Detailed analyses of the two octet-partitas, Partita in F, Op. 57 and Partita in E-flat, Op. 79, with discussion of thematic, harmonic, melodic, articulation, and formal characteristics illustrated through score examples. Examination of issues for a conductor to consider when approaching a performance of these works such as instrumentation (modern vs. period instruments, selecting 16-foot instrument), taking (or not taking) repeats with respect to form, interpreting articulations, determining metronomic tempos, ensemble balance, and style based on wind music of the Classical period. Also, how this music can (and why it should) be used by wind conductors as both a teaching supplement and a compositional model for pieces from …
Date: August 1995
Creator: Mailman, Matthew
System: The UNT Digital Library
Kurt Weill: a Song Composer in Wartime with Three Recitals of Selected Works of Mozart, Strauss, Bach, Schubert, and Others (open access)

Kurt Weill: a Song Composer in Wartime with Three Recitals of Selected Works of Mozart, Strauss, Bach, Schubert, and Others

During World War II the composer Kurt Weill was in America writing for the Broadway stage. On August 27, 1943, he became an American citizen and was eager to volunteer his talent to the American war effort. Among his many wartime musical contributions are fourteen songs, all with war-related texts, which can be divided into three distinct groups: the American propaganda songs (8), the German propaganda songs (2), and the Walt Whitman songs (4). It is the purpose of this paper to present a comparative analysis of a representative group of these war songs (two from each group) in order to illustrate Weill's musical versatility. The American propaganda songs were written in a purely popular song style; sung by Broadway actors; directed toward an American audience; with texts by the Broadway lyricist Oscar Hammerstein II and the Hollywood movie executive Howard Dietz. The German propaganda songs were written in a cabaret song style; sung in German by Weill's wife, Lotte Lenya; directed toward a German audience behind enemy lines; with texts by the German playwright Bertolt Brecht and the German cabaret writer Walter Mehring. The Four Walt Whitman Songs were written in a classical art song style; sung by classically …
Date: August 1993
Creator: Wyatt, Susan Beth Masters
System: The UNT Digital Library
The Solo Vocal Collections of Gerald R. Finzi Suitable for Performance by the High Male Voice, a lecture recital together with three recitals of selected works of J.S. Bach, H. Wolf, R. Vaughan Williams, A. Jolivet, F.J. Haydn, J. Brahms, L.V. Beethoven, R. Strauss, J.P. Rameau, M. Ravel, S. Barber, G. Faure (open access)

The Solo Vocal Collections of Gerald R. Finzi Suitable for Performance by the High Male Voice, a lecture recital together with three recitals of selected works of J.S. Bach, H. Wolf, R. Vaughan Williams, A. Jolivet, F.J. Haydn, J. Brahms, L.V. Beethoven, R. Strauss, J.P. Rameau, M. Ravel, S. Barber, G. Faure

A primary purpose of the study was to articulate the significance of these compositions to the twentieth century repertoire, with special attention given to Dies Natalis, recognized as an outstanding contribution to English music literature. Overviews and specific analyses, with pertinent performance applications and background data, fulfill this purpose and provide information of merit for the programming and performance of Finzi's songs for high male voice.
Date: August 1993
Creator: Germany, Samuel R.
System: The UNT Digital Library
The Flute: the Mechanical Improvements on the Body of the Orchestral Instrument since 1847 (open access)

The Flute: the Mechanical Improvements on the Body of the Orchestral Instrument since 1847

This thesis uniquely explains the mechanical improvements which have occurred to the flute over the last 147 years. Theobald Boehm revolutionized the flute by changing many of its components culminating with the 1847 model flute. Since that time other improvements have been made which enhance the flute's capabilities in terms of pitch, tone, timbre, and simplification offingeringpassages. Among those improvements which are discussed in the following pages are the Dorus G-sharp key, the gizmo key, the Cooper scale, and The Brogger Mekanik as well as the makers behind the various improvements including Vincent Dorus, George Barrere, and Albert Cooper.
Date: August 1994
Creator: Nussbaum, Carolyn
System: The UNT Digital Library
The Christmas Cantatas of Christoph Graupner (1683-1760): Volume 2 (open access)

The Christmas Cantatas of Christoph Graupner (1683-1760): Volume 2

An assessment of the contributions of Christoph Graupner's 1,418 extant church cantatas is enhanced by a study of his fifty-five surviving Christmas cantatas, written for the feasts of Christmas, St. Stephen's, St. John's, and the Sunday after Christmas. Graupner's training in Kirchberg, Reichenbach and at the Thomas School in Leipzig is recounted as well as his subsequent tenures in Hamburg and Darmstadt. This volume contains the appendices and bibliography.
Date: August 1992
Creator: Schmidt, René R.
System: The UNT Digital Library
The Fourteen Seréstas of Heitor Villa-Lobos (1887-1959) (open access)

The Fourteen Seréstas of Heitor Villa-Lobos (1887-1959)

The Fourteen Seréstas of Heitor Villa-Lobos comprise a group of songs that expresses Villa-Lobos's compositional technique for the voice. These songs are challenging as a topic because not much historical or analytical research has been done on them. I approach the topic by providing historical background on the modinha and how it relates to the serésta. This is followed by a descriptive analysis in the order of the set, which includes musical examples, chart diagrams, and comparisons of the seréstas to other works. I hope to have contributed valuable information to the research of these songs since Villa-Lobos wrote over ninety solo vocal songs which still await analysis and discussion. This thesis is a contribution toward narrowing this gap.
Date: August 1999
Creator: Sánchez, Noé
System: The UNT Digital Library
Expectation as Narrative Strategy in Richard Wagner's Parsifal (open access)

Expectation as Narrative Strategy in Richard Wagner's Parsifal

The story of Parsifal is presented in two manners: through action and through narrative. Using the formalist theories of Vladimir Propp, the overall narrative is articulated in three narrative episodes. This thesis interprets the structure of narrative episodes in Parsifal on the basis of expectation. Propp's theory of functions provides labels for an interpretive analysis. Levi-Strauss' reconstruction of Propp's functions into paired structures identifies key points in the drama as moments of "functional" saturation. This "functional" saturation coincides with Wagner's practice of Leitmotivic saturation. The semiotic theories of Charles Sanders Peirce, specifically his notion of sign, clarify the dense accumulation of meanings accrued by the Leitmotifs. Finally, Parsifal, as a "quest" for the unobtainable object, fits into the matrix of desire as formulated in the theories of Jacques Lacan.
Date: August 1997
Creator: Straughn, Greg, 1972-
System: The UNT Digital Library