Spencer, Andrew
Blackwell , 1993
Buku Teks
edited by Ricardo Aroca
Springer, 2012
eBooks
Roebuck, Julian B.
Charles C. Thomas, 1967
Buku Teks
Croft, William
Cambridge University Press, 1990
Buku Teks SO
Bauer, Laurie
Cambridge University Press, 2001
eBooks