Berkeley 4

Number of stars per data source

	Reference  478 :   29 stars
	Reference  510 : 1394 stars

478: Kharchenko N.V., Piskunov A.E., Röser S., Schilbach E., Scholz R.-D.; (2005) Astron. Astrophys. 438, 1163; Astrophysical parameters of galactic open clusters; 2005A&A...438.1163K
510: Maciejewski G., Niedzielski A.; (2007) Astron. Astrophys. 467, 1065; CCD BV survey of 42 open clusters; 2007A&A...467.1065M