White, James E.
Wadsworth and Cengage Learning, 2012
Buku Teks SO
edited by Christopher W. Gowans
Routledge, 2000
Buku Teks SO
Markham, Ian S.
Blackwell, 2007
Buku Teks SO
Banner, Michael
Cambridge University Press, 1999
Buku Teks SO
Altman, Matthew C
John Wiley & Sons, 2014
Buku Teks SO