Heinemann , 1982
Buku Teks
Smith, Adam, author
Modern Library, 1937
Buku Referensi
Isti Budhi Setiawati, author
Universitas Indonesia, 2013
UI - Tesis (Membership)
Ward, Barbara, author
W.W. Norton, 1962
Buku Teks
Porter, Michael E., author
The Free Press , 1990
Buku Teks