Jones, Bill, author
Manchester University Press, 1993
Buku Teks
Larson, Laurence M., author
Holt , 1926
Buku Teks
Burrows, Toby, author
The Howorth, 1989
Buku Teks
edited by Raoul P. Colinvaux
Stevens, 1975
Buku Teks
Allen, G.C., author
Longman, Green, 1952
Buku Teks