From Introduction: "Figure 1 shows the location of sources that have been either exploited or seriously considered at one time or another, super-imposed upon a map indicating by small letters the order of consumption of K2O in the leading States; the amount used in these States, together with the percentage of the total consumption of potash used as fertilizer in the United States in 1939, is given in table 1. Figure 2 shows the domestic production and total consumption of potassium salts, in terms of tons of K2O, with the value per unit at the plants, for each year since 1913. Considered together, these two figures tell a significant story."

Postcard from WASP Cornelia Yerkes to her parents discussing traveling to Buffalo to pick up a P-40 bound for Florida. The postcard features an image of a USAAF P-40 in flight.

Postcard from WASP Cornelia Yerkes to her parents discussing ferrying aircraft to Newark and traveling to Washington DC. The postcard features an image of a Douglas DC-3.

Postcard from Cornelia Yerkes to her parents discussing celebrating Christmas with her friend Bobby Willis' family. The postcard features an image of a TWA DC-3 in flight.