カクタスグラフ
1016/0095-8956(72)90040-8, MR0299523
↑ Harary, Frank; Uhlenbeck, George E. (1953), “On the number of Husimi trees, I”, Proceedings of the National Academy of Sciences 39 (4): 315–322, doi:10.1073/pnas.39.4.315, MR0053893, PMC 1063779, PMID 16589268, http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1063779
↑ Husimi, Kodi (1950), “Note on Mayers' theory of cluster integrals”, Journal of Chemical Physics 18 (5): 682–684, doi:10.1063/1.1747725, MR0038903
↑ See, e.g., MR0659742, a 1983 review by Robert E. Jamison of a paper using the other definition, which attributes the ambiguity to an error in a book by Mehdi Behzad and Gary Chartrand.