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AIR. (General Science)
…C. Zwart; drawings, Helen S. Zwart. Gerrit C. Zwart d.b.a. Visual Sciences; 11Jun37; MP7645.
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1937 |
Visual Sciences |
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ENERGY. (General Science)
…40 frames, 35 mm. Gerrit C. Zwart, d.b.a. Visual Sciences (Gerrit C. Zwart, author…
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1937 |
Visual Sciences |
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FIRE AND HEAT. (General Science)
…by Helen S. Zwart. Gerrit C. Zwart d.b.a. Visual Sciences (Gerrit C. Zwart, author…
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1937 |
Visual Sciences |
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FUNDAMENTALS OF BIOLOGY Visual Sciences.
…Johnson; drawings & letterings by Helen Smith Zwart. © Gerrit C. Zwart d.b.a. Visual Sciences; 10Nov69…
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1969 |
Gerrit C. Zwart d.b.a. Visual Sciences |
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LIGHT. (General Science)
…1937. Filmstrip, 40 frames. Gerrit C. Zwart, d.b.a. Visual Sciences (Gerrit C. Zwart, author…
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1937 |
Visual Sciences |
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MECHANICS (General Science, no. 1)
…40 frames, 35 mm. Gerrit C. Zwart, d.b.a. Visual Sciences (Gerrit C. Zwart, author…
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1937 |
Visual Sciences |
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OPTICAL ILLUSIONS.
…Drawings, Helen Smith Zwart. Gerrit C. Zwart, d.b.a. Visual Sciences (Gerrit C. Zwart, author…
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1937 |
Visual Sciences |
1 reel |
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Optical Illusions. Pt. 2
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1966 |
Visual Sciences |
34 fr |
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WATER. (General Science)
…Zwart; drawings by Helen S. Zwart. Gerrit C. Zwart d.b.a. Visual Sciences; 11Jun37; MP7646.
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1937 |
Visual Sciences |
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