Ed T. Prothro. Problem 10997. The American Mathematical Monthly, 110(2):156, 2003. [doi]
@article{Prothro03, title = {Problem 10997}, author = {Ed T. Prothro}, year = {2003}, url = {http://www.jstor.org/stable/3647784}, researchr = {https://researchr.org/publication/Prothro03}, cites = {0}, citedby = {0}, journal = {The American Mathematical Monthly}, volume = {110}, number = {2}, pages = {156}, }