REMOVE

1. Horseback riding.
2. Nitrate negatives
3. negative
4. Library of Congress Prints a …
5. between 1936 and 1942

WHAT

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