Drucker, Peter F. (Peter Ferdinand), 1909-2005, author
Heinemann Profesional , 1990
Buku Teks
Hanna, Williard A.
American University Field Staff, 1964
Buku Teks
James, Ann
Longman, 1998
Buku Teks
Sleeper, Jim
W.W.Norton, 1990
Buku Teks
Mills, Stephen
Penguin Books, 1986
Buku Teks