NGC 2251

Number of stars per data source

	Reference   97 :    2 stars
	Reference  206 :    1 star
	Reference  221 :    1 star
	Reference  389 :    2 stars
	Reference 1041 :    2 stars

97: Young A., Martin A.E.; (1973) Astrophys. J. 181, 805; A search for Ap stars in open clusters; 1973ApJ...181..805Y
206: Hiltner W.A.; (1956) Astrophys. J. Suppl. 2, 389; Photometric, polarization and spectrographic observations of O and B stars; 1956ApJS....2..389H
221: Sowell J.R; (1987) Astrophys. J. Suppl. 64, 241; Yellow evolved stars in open clusters; 1987ApJS...64..241S
389: van Rensbergen W., Hammerschlag G., van den Heuvel E.P.J; (1978) Astron. Astrophys. 64, 131; Spectroscopic studies of open clusters - A search for Ap stars; 1978A&A....64..131V
1041: Abt H.A.; (1985) Astrophys. J. 294, L103; The spectra and ages of blue stragglers; 1985ApJ...294L.103A