Mark Walters. Rectangles as sums of squares. Discrete Mathematics, 309(9):2913-2921, 2009. [doi]
@article{Walters09, title = {Rectangles as sums of squares}, author = {Mark Walters}, year = {2009}, doi = {10.1016/j.disc.2008.07.028}, url = {http://dx.doi.org/10.1016/j.disc.2008.07.028}, researchr = {https://researchr.org/publication/Walters09}, cites = {0}, citedby = {0}, journal = {Discrete Mathematics}, volume = {309}, number = {9}, pages = {2913-2921}, }