REMOVE

1. machinery
2. suns
3. hats
4. sky
5. trees

WHAT

1. black-and-white film (1)
2. clouds (1)
3. fields (land) (1)
4. hills (1)
5. horizon line (1)
6. landscapes (representatio … (1)
7. plants (1)
8. silhouettes (1)
9. soil (1)
10. sunlight (1)
11. Visual Works (hierarchy n … (1)
12. woods (plant communities) (1)

WHO

1. Campbell, Sandra L. Still (1)
2. Sandra L. Still Campbell; … (1)

WHEN

1. 1961 (1)
2. after 1961 (1)