1. On sums of an even number of squares, and an even number of triangular numbers: an elementary approach based on Ramanujan's 1c1 summation formula;Cooper,2001
2. Sums of five, seven and nine squares;Cooper;Ramanujan J.,2002
3. On the number of representations of certain integers as sums of 11 or 13 squares;Cooper;J. Number Theory,2003
4. Neue theoreme der hö heren arithmetik;Eisenstein;J. Reine Angew. Math.,1847
5. Disquisitiones Arithmeticae;Gauss,1801