Kohler, R. E. Subspecies classification and biological survey, 1850s-1930s: Robert E. Kohler. Spaces of classification.(2003).
Citazione stile Chigago Style (17a edizione)Kohler, Robert E. "Subspecies Classification and Biological Survey, 1850s-1930s: Robert E. Kohler." Spaces of Classification.(2003) .
Citatione MLA (8a ed.)Kohler, Robert E. "Subspecies Classification and Biological Survey, 1850s-1930s: Robert E. Kohler." Spaces of Classification.(2003), .
Attenzione: Queste citazioni potrebbero non essere precise al 100%.