Sachs, Ignacy
Cambridge University Press , 1987
Buku Teks
Kotler, Philip, author
The Free Press , 1997
Buku Teks
Pitt, David C., author
Pergamon Press, 1976
Buku Teks
Pitt, David C., author
Pergamon Press, 1976
Buku Teks
edited by I. Livingstone
Penguin Books, 1971
Buku Teks