edited by Brian M. Fagan
Thames and Hudson, 2007
Buku Referensi
edited by Mari Pritchard Parker, Elvio Angeloni
McGraw-Hill, 2013
Buku Teks SO
Artikel Jurnal
Staeck, John P.
Mayfield Publishing Company, 2002
Buku Teks SO
Shanks, Michael
Routledge , 1992
Buku Teks SO