Vajda, S.
John Wiley & Sons, 1978
Buku Teks
The Association of Southeast Asian Institutons of Higher Learning (ASAIHL)
Gadjah Mada University, 1985
Buku Referensi
STAID, BBPT, 1993
Buku Referensi
Behrman, Jack N., author
Oelgeschlager, Gunn & Gunn & Hain , 1980
Buku Teks
Wadsworth, 1962
Buku Teks