Horrell, Edward, author
American Management Association, 2006
eBooks
Universitas Indonesia, 2006
UI - Skripsi (Membership)
Bob, Clifford, author
Cambridge University Press, 2005
Buku Teks
Bomans, Godfried, 1913-1971, author
Elsevier, 1972
Buku Teks
Dull, Charles E.
Holt, Rinehart and winston, 1963
Buku Teks