Theory of ballooning. (open access)

Theory of ballooning.

A general guide to piloting a free balloon.
Date: April 25, 1940
Creator: United States. War Department.
System: The UNT Digital Library
Powdery Mildew of Ornamental Plants. (open access)

Powdery Mildew of Ornamental Plants.

Describes the powdery mildew fungus and methods for its control.
Date: April 1940
Creator: Weiss, Freeman
System: The UNT Digital Library
Work of the United States Forest Service. (open access)

Work of the United States Forest Service.

Discusses forest depletion and provides a history of forest conservation efforts by the United States government. Describes the work of the the Civilian Conservation Corps and other emergency projects, and discusses forest and range research.
Date: April 1940
Creator: United States. Forest Service.
System: The UNT Digital Library