Jacques R. Helfer (Helfer, Jacques R.)

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  How to Know the Grasshoppers, Crickets, Cockroaches and Their Allies
  by Jacques R. Helfer
  Softcover, Dover Pubns, ISBN 0486253953 (0-486-25395-3)
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  How to Know the Rocks and Minerals
  by Jacques R. Helfer
  Softcover, W. C. Brown Co, ISBN 0697048268 (0-697-04826-8)