Harrison, Thomas L., author
Kaifa, 2008
Buku Teks
Siahaan, Ashoka, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 1988
UI - Skripsi Membership
Moustakas, Clark E.
Sage Publications, 1994
Buku Teks
Stefan Engeser, editor
[Springer, ], 2012
eBooks
Dieter Lohmar
Springer Science, 2012
eBooks