NGC 6531

Number of stars per data source

	Reference  202 :    2 stars
	Reference  206 :    1 star
	Reference  207 :   12 stars
	Reference  999 :    2 stars

References

 202
Morgan W.W., Code A.D., Whitford A.E.
(1955) Astrophys. J. Suppl. 2, 41
Studies in galactic structure. II. Luminosity classification for 1270 blue giant stars
1955ApJS....2...41M
 206
Hiltner W.A.
(1956) Astrophys. J. Suppl. 2, 389
Photometric, polarization and spectrographic observations of O and B stars
1956ApJS....2..389H
 207
Hoag A.A., Applequist L.
(1965) Astrophys. J. Suppl. 12, 215
Distance moduli of open clusters
1965ApJS...12..215H
 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