REMOVE

1. Walking.
2. Nitrate negatives
3. National parks & reserves.
4. Library of Congress Prints a …
5. Genthe, Arnold
6. 1869-1942

WHAT

1. National parks & reserves … (1)
2. Nitrate negatives (1)
3. Photographs (1)
4. negative (1)

WHO

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

WHEN

1. 1903 (1)
2. 1906 (1)
3. between 1903 and 1906 (1)