Turner, D. G. Galactic clusters with associated Cepheid variables. I - NGC 6087 and S Normae. S. 111–118. Astronomical Journal [online]. Červenec 1986 [cit. 2016-05-06]. Roč. 92, s. 111–118. Dostupné online. doi:10.1086/114141. Bibcode1986AJ.....92..111T. (anglicky)
Majaess, Daniel J.; Turner, David G.; Lane, David J. In Search of Possible Associations between Planetary Nebulae and Open Clusters. S. 1349–1360. Publications of the Astronomical Society of the Pacific [online]. Prosinec 2007 [cit. 2016-05-06]. Roč. 119, čís. 862, s. 1349–1360. Dostupné online. doi:10.1086/524414. Bibcode2007PASP..119.1349M. (anglicky)
Turner, D. G. Galactic clusters with associated Cepheid variables. I - NGC 6087 and S Normae. S. 111–118. Astronomical Journal [online]. Červenec 1986 [cit. 2016-05-06]. Roč. 92, s. 111–118. Dostupné online. doi:10.1086/114141. Bibcode1986AJ.....92..111T. (anglicky)
Majaess, Daniel J.; Turner, David G.; Lane, David J. In Search of Possible Associations between Planetary Nebulae and Open Clusters. S. 1349–1360. Publications of the Astronomical Society of the Pacific [online]. Prosinec 2007 [cit. 2016-05-06]. Roč. 119, čís. 862, s. 1349–1360. Dostupné online. doi:10.1086/524414. Bibcode2007PASP..119.1349M. (anglicky)