Lorentzen, Karen M., author
Warren H. Green, 1988
Buku Teks
Metzger, Norman
Spectrum Publication, 1975
Buku Teks
edited by Gordon Stevenson and Sally Stevenson
The Haworth Press , 1984
Buku Teks
Reynolds, Amanda, author
Open universtity press , 2000
Buku Teks
editors, Stephen J. Williams, Paul R. Torrens
Delmar , 1998
Buku Teks