Meier, W. H. D., & Schoemaker, L. M. (1931). Essentials of biology. Ginn.
Lua i Stíl Chicago (17ú heag.)Meier, William Herman Dietrich, agus Lois Meier Schoemaker. Essentials of Biology. Boston: Ginn, 1931.
Lua MLA (8ú heag.)Meier, William Herman Dietrich, agus Lois Meier Schoemaker. Essentials of Biology. Ginn, 1931.
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