Guinagh, Kevin, author
New York, The H.W. Wilson, 1965
Buku Referensi
revised and edited by Eugene Ehrlich
Penguin Books, 1993
Buku Referensi
Bliss, Alan J., author
Routledge & Kegan Paul, 1966
Buku Referensi
Signet Book, 1962
Buku Teks
Albert, Loy Morehead, editors
New American Library, 1972
Buku Referensi