Westview Press, 1980
Buku Teks
Bonner, Hubert
American Book Company, 1953
Buku Teks
Farris, Pamela J., author
New York, 2001
Buku Teks
Goscha, Christopher E., author
Nias Press, 2012
Buku Referensi
Fishman, Joshua A., author
Newbury House Publishers, 1972
Buku Teks