Negative holder
United States Patent 2154510

Inventors:
Rollin, King
Boaden, Earl T.
Publication Date:
04/18/1939
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Assignee:
Rollin, King
Boaden, Earl T.
Primary Class:
40/771
Other Classes:
D19/26, 40/709, 383/106, 383/38
International Classes:
G03B21/64; G03B21/54