REMOVE

1. streets
2. rock
3. national parks
4. 1973

WHAT

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

More 

WHERE

1. New Windsor, Maryland (1)

WHO

1. Campbell, Sandra L. Still (1)
2. Clyfford Still; Still, Cl … (1)
3. Sandra L. Still Campbell; … (1)
4. Still, Clyfford (1)

Less

WHEN

1. 1967 (2)
2. 1969 (1)