@article{Callan04,
  title = {Problem 11091},
  author = {David Callan},
  year = {2004},
  url = {http://www.jstor.org/stable/4145078},
  researchr = {https://researchr.org/publication/Callan04},
  cites = {0},
  citedby = {0},
  journal = {The American Mathematical Monthly},
  volume = {111},
  number = {6},
  pages = {534},
}