Artikel Jurnal
Siahaan, Nommy H.T., author
Erlangga, 2004
Buku Teks
Arya Hadi Dharmawan, author
[Publisher not identified], [Date of publication not identified]
Artikel Jurnal
Siahaan, Nommy H.T., author
Erlangga, 1987
Buku Teks
Shiva, Vandana, author
Yayasan obor Indonesia, 1998
Buku Teks