^Notes on the NGC objects, particularly those missing, misidentified, or otherwise unusual (ngcnotes.all).. Historically-aware NGC/IC Positions and Notes. [2019-08-11]. (原始内容存档于2018-01-30).
^A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association, Martins, F.; Mahy, L.; Hillier, D. J.; Rauw, G., Astronomy and Astrophysics538, pp. A39, Bibcode:2012A&A...538A..39M, doi:10.1051/0004-6361/201117458.