REMOVE

1. barriers
2. rock
3. soil
4. 1956

WHAT

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

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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)

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WHEN

1. 1969 (1)