Ruprecht 91

Number of stars per data source

	Reference   89 :    1 star
	Reference  999 :    7 stars

89: Humphreys R.M., Strecker D.W., Ney E.P.; (1972) Astrophys. J. 172, 75; Spectroscopic and photometric observations of M supergiants in Carina; 1972ApJ...172...75H
999: Houk N., Cowley A.P., Smith-Moore M.; University of Michigan (Ann Arbor) Vol 1 (1975), Vol 2 (1978), Vol 3 (1982), Vol 4 (1988), Vol 5 (1999); The University of Michigan Catalogue of two-dimensional Spectral Types for the HD stars; 1975mctd.book.....H