REMOVE

1. trucks
2. workers
3. sky
4. roads
5. plants
6. parking lots

WHAT

1. birds (animals) (1)
2. exterior views (1)
3. geese (animals) (1)
4. rivers (1)
5. silver gelatin (1)
6. travel (1)
7. trees (1)
8. Visual Works (hierarchy n … (1)
9. water (1)

WHO

1. Clyfford Still; Still, Cl … (1)
2. Garske, Patricia; Patrici … (1)
3. Still, Clyfford (1)
4. Still, Patricia Alice Gar … (1)

More 

WHEN

1. 1956 (1)
2. c. 1956 (1)