Pandit, Sudhakar M.
New York John Wiley and Sons 1983,
Buku Teks
Sobotka, Zdenek, author
Elsevier, 1984
Buku Teks
Sitompul, S.M., author
Gadjah Mada University Press , 1995
Buku Teks
Panggabean, Padro, author
1987
UI - Skripsi (Membership)
Fairclough, Norman, author
Rotledge, 2010
Buku Teks