NGC 6604

Number of stars per data source

	Reference  275 :    1 star
	Reference  425 :    3 stars

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
425: FitzGerald M.P., Luiken M., Maitzen H.M., Moffat A.F.J.; (1979) Astron. Astrophys. Suppl. 37, 345; Analysis of the results of MK classification of 176 stars in 37 southern open clusters; 1979A&AS...37..345F