Entwistle, Jill, author
New York Roto vision SA 1999,
Buku Referensi
Entwistle, Jill, author
Roto vision SA, 1999
Buku Referensi
Sobel, Michael I., author
University of Chicago, 1987
Buku Teks
Mueller, Conrad G.
Time Incoporated, 1966
Buku Teks
Supriyanto, author
Universitas Indonesia, 1992
UI - Tesis (Membership)