APA-referens (7:e uppl.)

Hawkins, J., Hughes, C., & Scotland, R. (1997). Primary homology assessment, characters and character states.

Chicago-referens (17:e uppl.)

Hawkins, J., C. Hughes, och R. Scotland. Primary Homology Assessment, Characters and Character States. 1997.

MLA-referens (9:e uppl.)

Hawkins, J., et al. Primary Homology Assessment, Characters and Character States. 1997.