Gough, Ian, author
Macmillan, 1992
Buku Teks
Nath, S. K.
Augustus M. Kelley, 1969
Buku Teks
Little, Ian M.D.
The Clarendon Press, 1957
Buku Teks
edited by Thomas and Dorothy Wilson
Longman, 1991
Buku Teks
Jansson, Bruce S., author
Thompson, 2005
Buku Teks