G & C Merriam Co., 1961
Buku Referensi
Merriam-Webster, Incorporated, 1996
Multimedia
Williamson, David, author
Currency Press, 1978
Buku Teks
Milroy, Patrick, author
Ward Lock Book, 1994
Buku Referensi
Nurayla Arnas Nasution, author
2012
UI - Tesis (Membership)