Monosson, Emily
Island Press, 2012
eBooks
Kelly, Mahlon G.
Houghton Miffiln, 1975
Buku Teks
edited by Bernard Stonehouse and Christopher M. Perrins
University Park Press, 1979
Buku Teks
Geist, Valerius
Springer, 1978
Buku Teks
Pianka, Eric R.
Harper & Row, 1988
Buku Teks