REMOVE

1. Photographs
2. Show jumping.
3. negative
4. Library of Congress Prints a …
5. Genthe, Arnold
6. between 1933 and 1942

WHAT

1. Horse shows. (1)
2. Nitrate negatives (1)
3. Show jumping. (1)

WHO

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

WHEN

1. 1869-1942 (1)
2. 1933 (1)
3. 1942 (1)
4. between 1933 and 1942 (1)