Williams, David J., author
Prentice - Hall , 1971
Buku Teks
Ahluwalia, V.K., author
Taylor and Francis, 2008
Buku Teks
edited by P.E. Irving and C. Soutis
Woodhead, 2015
eBooks
Ivanov, V.S., author
Netherlands VSP, 1992
Buku Teks
Williams, Peter J
Longman, 1982
Buku Teks