Enger, E. D., Kormelink, J. R., Ross, F., & Smith, R. J. (1991). Concepts in biology (Sixth edition.). Wm. C. Brown.
Citazione stile Chigago Style (17a edizione)Enger, Eldon D., J. Richard Kormelink, Frederick Ross, e Rodney J. Smith. Concepts in Biology. Sixth edition. Dubuque, Iowa: Wm. C. Brown, 1991.
Citatione MLA (9a ed.)Enger, Eldon D., et al. Concepts in Biology. Sixth edition. Wm. C. Brown, 1991.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.