1. Alter, G., Ruprecht, J., & Vanysek, V. 1970, in Catalogue of star clusters and associations + supplements, 2nd ed. (Budapest: Akad. Kiado)
2. A Catalogue of infrared star clusters and stellar groups
3. Binney, J., & Merrifield, M. 1998, in Galactic Astronomy (Princeton, NJ: Princeton University Press), Princeton series in astrophysics, QB857.B522
4. Near-infrared imaging of compact HII regions in Cygnus X