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