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Please read BHL's Acknowledgment of Harmful Content
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  1. By: Roark, R. C. (Ruric Creegan) - United States. Bureau of Chemistry and Soils. Insecticide Division. - United States. Bureau of Entomology and Plant Quarantine. Insecticide Division.
    Publication info: Washington, D.C, [The Bureau], 1934-1935
    Holding Institution: U.S. Department of Agriculture, National Agricultural Library