REMOVE

1. Photographs
2. Nitrate negatives
3. Library of Congress Prints a …
4. between 1936 and 1942

WHAT

1. Horseback riding. (1)
2. Nitrate negatives (1)
3. Portrait photographs (1)
4. negative (1)

WHO

1. Genthe, Arnold (1)
2. Library of Congress Print … (1)

WHEN

1. 1869-1942 (1)
2. 1936 (1)
3. 1942 (1)
4. between 1936 and 1942 (1)