Knutsen, Torbjorn L.
Manchester University Press, 1992
Buku Teks
Hobden, Stephen
Routledge, 1998
Buku Teks
Malchow, Howard L., author
Bloomsbury Academic, an imprint of Bloomsbury Pub, 2016
Buku Teks
Lairson, Thomas D., author
Thomson, 2003
Buku Teks
Gray, Colin S., author
Routledge, 2012
Buku Teks