Gallagher & Grebel (2002). “Extragalactic Star Clusters: Speculations on the Future”. Extragalactic Star Clusters, IAU Symposium: 207. arXiv:astro-ph/0109052. Bibcode: 2002IAUS..207..745G.
Johnson (2004). “Extragalactic Ultracompact HII Regions: Probing the Birth Environments of Super Star Clusters”. Astronomical Society of the Pacific Conference Series527: 322. arXiv:astro-ph/0405125. Bibcode: 2004ASPC..322..339J.
Astrophysical Journal, "Star Formation in R136: A Cluster of O3 Stars Revealed by Hubble Space Telescope Spectroscopy", Massey, Philip; Hunter, Deidre A., 01/1998, v.493, p.180, doi:10.1086/305126 , Bibcode: 1998ApJ...493..180M
Gallagher & Grebel (2002). “Extragalactic Star Clusters: Speculations on the Future”. Extragalactic Star Clusters, IAU Symposium: 207. arXiv:astro-ph/0109052. Bibcode: 2002IAUS..207..745G.
Johnson (2004). “Extragalactic Ultracompact HII Regions: Probing the Birth Environments of Super Star Clusters”. Astronomical Society of the Pacific Conference Series527: 322. arXiv:astro-ph/0405125. Bibcode: 2004ASPC..322..339J.
Astrophysical Journal, "Star Formation in R136: A Cluster of O3 Stars Revealed by Hubble Space Telescope Spectroscopy", Massey, Philip; Hunter, Deidre A., 01/1998, v.493, p.180, doi:10.1086/305126 , Bibcode: 1998ApJ...493..180M