Plummer, Alfred, author
Sir Isaac Pitman & Sons , 1951
Buku Teks
Globerman, Steven
Prentince-Hall, 1986
Buku Teks
Johnson, Debra, author
Routledge, Taylor & Francis group, 2003
Buku Teks
Levi, Maurice D., 1945-, author
McGraw-Hill, 1983
Buku Teks
Ball, Donald A., author
Business Publications, 1985
Buku Teks