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Jacques R. Helfer

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How to Know the Grasshoppers, Cockroaches and Their Allies Pictured Key Nature Series
How to Know the Rocks and Minerals
How to Know the Grasshoppers, Cockroaches and Their Allies Pictured-keys for Identifying Many of the Grasshoppers, Crickets, Katydids, Earwigs, Termites, Cockroaches, Praying Mantids, Rock-crawlers, and Walkingsticks Occuring in North America, North of Mexico
How to Know the Grasshoppers,cock-roaches and Their Allies