Verma, Nirmal
Indigo, 2002
Buku Teks
Scholberg, H.C.
Oxford University Press, 1950
Buku Teks
Pray, Bruce R.
University of California Press , 1970.
Buku Teks
Diamond, 2001
Buku Referensi
Agrawal, Giriraj Sharan
Diamond pocket books, 2001
Buku Referensi