REMOVE

1. Horse shows.
2. Genthe, Arnold
3. Library of Congress Prints a …
4. 1933 or 1934

WHAT

1. Horse shows. (1)
2. Nitrate negatives (1)
3. Photographs (1)
4. negative (1)

WHO

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

WHEN

1. 1869-1942 (1)
2. 1933 (1)
3. 1933 or 1934 (1)