REMOVE

1. Walking.
2. negative
3. Photographs
4. National parks & reserves.
5. Library of Congress Prints a …
6. between 1903 and 1906
7. 1906

WHAT

1. National parks & reserves … (1)
2. Nitrate negatives (1)

WHO

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

WHEN

1. 1869-1942 (1)
2. 1903 (1)
3. between 1903 and 1906 (1)