Hamilton, David
Random House, 1968
Buku Teks
Olga Aikin
IPM, 1994
Buku Teks
Clarke, Linda, author
Institute of Personnel and Development, 1993
Buku Teks
Meier, Gerald M., author
Oxford University Press, 1979
Buku Teks
Muhammad Yunus, author
PublicAffairs, 1987
Buku Teks