REMOVE

1. boys
2. trees
3. hills
4. workers
5. rubbish

WHAT

1. Nespelem (1)
2. Visual Works (hierarchy n … (1)
3. automobiles (1)
4. black-and-white film (1)
5. buildings (structures) (1)

More 

WHERE

1. Nespelem, Washington (1)

WHO

1. Clyfford Still; Still, Cl … (1)
2. Still, Clyfford (1)

WHEN

1. 1937 (1)
2. 1938 (1)
3. ca. 1937 - 1938 (1)