Não informado. (1937). Plant inventory. Bureau of Plant Industry, Soils and Agricultural Engineering.
Chicago-referens (17:e uppl.)Não informado. Plant Inventory. Washington: Bureau of Plant Industry, Soils and Agricultural Engineering, 1937.
MLA-referens (8:e uppl.)Não informado. Plant Inventory. Bureau of Plant Industry, Soils and Agricultural Engineering, 1937.
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