Donald E. Knuth, O. P. Lossers. Partitions of a Circular Set: 11151. The American Mathematical Monthly, 114(3):265-266, 2007. [doi]
@article{KnuthL07, title = {Partitions of a Circular Set: 11151}, author = {Donald E. Knuth and O. P. Lossers}, year = {2007}, url = {http://www.jstor.org/stable/27642185}, researchr = {https://researchr.org/publication/KnuthL07}, cites = {0}, citedby = {0}, journal = {The American Mathematical Monthly}, volume = {114}, number = {3}, pages = {265-266}, }