Spero, Joan Edelman, author
Wadsworth, 2010
Buku Teks
Spero, Joan Edelman, author
Routledge , 1997
Buku Teks
Hodgson, John S., author
Prentice-Hall, 1983
Buku Teks
Jackson, John H., author
West Publishing, 2013
Buku Teks
Kohona, Palitha T.B., author
Martinus Nijhoff, 1985
Buku Teks