The University Press of Kentucky, 1972
Buku Teks
Aron, Raymond, author
Doubleday and Company, Inc., 1954
Buku Teks
Keylor, William R., 1944-, author
Oxford University Press, 1996
Buku Teks
Salem Press , 1992
Buku Referensi
Salem Press , 1992
Buku Referensi