Mayr, E. (1999). Systematics and the origin of species, from the viewpoint of a zoologist (1st Harvard University Press pbk. ed.). Cambridge, Mass.: Harvard University Press.

Mayr, Ernst. Systematics and the Origin of Species, From the Viewpoint of a Zoologist. 1st Harvard University Press pbk. ed. Cambridge, Mass.: Harvard University Press, 1999.

Mayr, Ernst. Systematics and the Origin of Species, From the Viewpoint of a Zoologist. 1st Harvard University Press pbk. ed. Cambridge, Mass.: Harvard University Press, 1999.