Henschel, Astrid
Passport Books, 1994
Buku Teks
Weston, Marie-Therese
NTC Publishing Group, 1994
Buku Teks
Dina
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 1999
UI - Skripsi Membership
McKaughan, Howard P.
Institute of National Language, 1958
Buku Teks
Cowie, A.P.
Oxford University Press, 1993
Buku Referensi