edited by Robert Finch and John Elder
W.W. Norton, 2002
Buku Teks
Quammen, David
Schocken Books , 1985
Buku Teks
Yates, Steve
Facts On File, 1992
Buku Referensi
MacKinnon, Kathy
Gramedia Pustaka Utama, 1992
Buku Teks
Bangs, Richard
Siera Club Books, 1988
Buku Teks