Howard, John Tasker
Thomas Y. Crowell, 1946
Buku Teks SO
Chang, Garma C.C.
The Pennsylvania State University Press, 1971
Buku Teks SO
Resnicoff, Samuel
Law-Arts Publishers, 1969
Buku Teks
Artikel Jurnal
Edited by John E. Jones and J. William Pfeiffer
University Associates, 1973
Buku Teks SO