Agrawal, Giriraj Sharan
Diamond pocket books, 2001
Buku Referensi
Diamond, 2001
Buku Referensi
Pray, Bruce R.
University of California Press , 1970.
Buku Teks
Gurtu, Madhu
Munshiram Manoharlal, 1992
Buku Teks SO
Blakeney, E.H.
J.M. Dent & Sons, 1952
Buku Referensi