John, V.B., author
Macmillan, 1977
Buku Teks
John, Vernon, author
Macmillan, [Date of publication not identified]
Buku Teks
Callister, William D., Jr., 1940-, author
John Wiley & Sons, 2008
Buku Teks
Steeds, W.
Longman, 1964
Buku Teks
Henkel, Daniel P., author
McGraw-Hill, Higher Education, 2002
Buku Teks