Dobie, Ann B.
Wadsworth and Cengage Learning, 2012
Buku Teks SO
Ryan, Michael
Blackwell, 2007
Buku Teks SO
Ryan, Michael, 1951-
Wiley-Blackwell, 2017
Buku Teks SO
Johns Hopkins University Press, 1983
Majalah, Jurnal, Buletin
edited by Ralph Cohen
Sheridan Press, 1989
Buku Referensi