Cita APA (7th ed.)

Kohler, R. E. Subspecies classification and biological survey, 1850s-1930s: Robert E. Kohler. Spaces of classification.(2003).

Cita Chicago (17th ed.)

Kohler, Robert E. "Subspecies Classification and Biological Survey, 1850s-1930s: Robert E. Kohler." Spaces of Classification.(2003) .

Cita MLA (8th ed.)

Kohler, Robert E. "Subspecies Classification and Biological Survey, 1850s-1930s: Robert E. Kohler." Spaces of Classification.(2003), .