Helman, Cesil G., 1944-, author
Boston Wright, 1990
Buku Teks
Ketchum, Paul A., author
John Wiley & Sons, 1984
Buku Teks
Bond, John
Churchill Livinstone , 1994
Buku Teks
Barry, Anne-Marie, author
SAGE Publications Ltd, 2016
Buku Teks
Weis, Gregory L, author
Prentice Hall, 1996
Buku Teks