COLLINDER, Per. On Structural Properties of Open Galactic Clusters and their Spatial Distribution. Catalog of Open Galactic Clusters. S. B1-B46. Annals of the Observatory of Lund [online]. 1931 [cit. 2019-10-02]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
GRUBISSICH, C. Three-colour photometry of the two galactic star clusters NGC 559 and NGC 637. S. 99–107. Astronomy and Astrophysics Supplement Series [online]. Červenec 1975 [cit. 2019-10-02]. Roč. 21, s. 99–107. Dostupné online. Bibcode1975A&AS...21...99G. (anglicky)
PAULS, T.; VAN GORKOM, J. H.; GOSS, W. M., et al. Westerbork and VLA observations of G 127.1+0.5. S. 120–123. Astronomy and Astrophysics [online]. Srpen 1982 [cit. 2019-10-02]. Roč. 112, čís. 1, s. 120–123. Dostupné online. Bibcode1982A&A...112..120P. (anglicky)
COLLINDER, Per. On Structural Properties of Open Galactic Clusters and their Spatial Distribution. Catalog of Open Galactic Clusters. S. B1-B46. Annals of the Observatory of Lund [online]. 1931 [cit. 2019-10-02]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
GRUBISSICH, C. Three-colour photometry of the two galactic star clusters NGC 559 and NGC 637. S. 99–107. Astronomy and Astrophysics Supplement Series [online]. Červenec 1975 [cit. 2019-10-02]. Roč. 21, s. 99–107. Dostupné online. Bibcode1975A&AS...21...99G. (anglicky)
PAULS, T.; VAN GORKOM, J. H.; GOSS, W. M., et al. Westerbork and VLA observations of G 127.1+0.5. S. 120–123. Astronomy and Astrophysics [online]. Srpen 1982 [cit. 2019-10-02]. Roč. 112, čís. 1, s. 120–123. Dostupné online. Bibcode1982A&A...112..120P. (anglicky)