edited by Susan E. Israel, Gerald G. Duffy
Routledge, 2009
Buku Referensi
Lawrwncw Erlbaum Associates, Inc, 2005
Buku Teks
Heredia, Roberto R
Springer International Publishing, 2016
eBooks
Gardiner, Peter D.R.
Charles Scribner's Sons, 1971
Buku Teks SO
McGillivray, James H.
American Book, 1960
Buku Teks SO