Borgo, Mauro
[, Springer], 2012
eBooks
Surwillo, Walter W.
Ablex, 1990
Buku Teks SO
Kristine Krapp, Editor
Thomson Gale, 2004
Buku Referensi
Embretson, Susan E.
Lawrence erlbaum assossiate, 2000
Buku Teks SO
editors, Gerald P. Koocher, John C. Norcross, Sam S. Hill, III
Oxford University Press, 2005
Buku Teks