Kelly, Robert L.,author
Wadsworth, 2010
Buku Teks
SPAFA, 1984
Buku Referensi
edited by Mari Pritchard Parker, Elvio Angeloni
McGraw-Hill, 2013
Buku Teks
Mouton, Jane S., author
Hague, 1968
Buku Teks
Kaplan, Abby, author
Cambridge University Press, 2016
Buku Teks