Roberts, Margaret
Hutchinson & Co (Publisher) LTD, 1974
Buku Teks
James D. Williams, editor
Wiley-Blackwell, 2009
Buku Teks
Ireland, Kenneth F., author
Springer-Verlag, 1990
Buku Teks
Crocker, Linda M., author
Holt, Rinehart, and Winston, 1986
Buku Teks
University of California Press, 1996
Buku Teks