Gopal, Madan (1990). K.S. Gautam (ed.). India through the ages. Publication Division, Ministry of Information and Broadcasting, Government of India. p. 79.
The example in this section is given (with notation for k, for m, etc.) in: Michael J. Jacobson; Hugh C. Williams (2009), Solving the Pell equation, Springer, p. 31, ISBN978-0-387-84922-5