NGC 6520

Number of stars per data source

	Reference  999 :    2 stars
	Reference 1045 :   31 stars

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
1045: Odell A.P.; (2014) Astron. J. 147, 7; A New Look at Open Cluster NGC 6520; 2014AJ....147....7O