Cohen, Morris L.
West Publishing Co., 1989
Buku Teks SO
Foster, Lynn
West Publishing Company, 1983
Buku Teks SO
edited ny Jeffrey T. Huber
The Haworth Press, 1992
Buku Referensi
Burrington, Gillian A.
Pergamon Press, 1972
Buku Teks SO
Dewey, Barbara I.
Oryx Press, 1987
Buku Teks SO