VizieR online Data Catalogue associated with article published in journal Astronomical Journal (AAS) with title 'The HII Regions of the Galaxy M101' (bibcode: 1992AJ....104...92S)
Scowen, P. A. (Creator), Dufour, R. J. (Creator), Hester, J. J. (Creator) (1995). HII Regions Properties in M101. Strasbourg Astronomical Data Center. 10.26093/cds/vizier.51040092