References
- L. E. Dickson, Modern Elementary Theory of Numbers, University of Chicago Press, 1939.
- L. E. Dickson, Introduction to the Theory of Numbers, University of Chicago Press, 1929.
- L. E. Dickson, History of the Theory of Numbers, Carnegie Institute, Washington, Chelsea, 1952.
- Robert Spira, Sums of Two Squares and Brahmagupta's Formula, Dissertation, University of California at Berkeley, 1962.