Groot, B. d. (1961). Libido and semen characteristics of bull twins with special regard to genotypic and environmental variability. G. van Dijk.
Lua i Stíl Chicago (17ú heag.)Groot, Bram de. Libido and Semen Characteristics of Bull Twins with Special Regard to Genotypic and Environmental Variability. Breukelen: G. van Dijk, 1961.
Lua MLA (8ú heag.)Groot, Bram de. Libido and Semen Characteristics of Bull Twins with Special Regard to Genotypic and Environmental Variability. G. van Dijk, 1961.
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