NGC 6530

Number of stars per data source

	Reference   69 :   24 stars
	Reference  213 :    3 stars
	Reference  275 :    2 stars
	Reference  999 :    1 star

69: Hiltner W.A., Morgan W.W., Neff J.S.; (1965) Astrophys. J. 141, 183; Studies in spectral classification. II. The HR diagram of NGC 6530; 1965ApJ...141..183H
213: Garrison R.F., Hiltner W.A., Schild R.E.; (1977) Astrophys. J. Suppl. 35, 111; MK spectral classifications for southern OB stars; 1977ApJS...35..111G
275: Walborn N.R.; (1972) Astron. J. 77, 312; Spectral classification of OB stars in both hemisphere and the absolute-magnitude calibration; 1972AJ.....77..312W
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