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. 2021-12-07]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
REIPURTH, Bo. The Young Cluster NGC 6604 and the Serpens OB2 Association. S. 590. Handbook of Star Forming Regions [online]. Prosinec 2008 [cit. 2021-12-07]. Roč. 5, s. 590. Dostupné online. Bibcode2008hsf2.book..590R. (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. 2021-12-07]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
REIPURTH, Bo. The Young Cluster NGC 6604 and the Serpens OB2 Association. S. 590. Handbook of Star Forming Regions [online]. Prosinec 2008 [cit. 2021-12-07]. Roč. 5, s. 590. Dostupné online. Bibcode2008hsf2.book..590R. (anglicky)
u-strasbg.fr
simbad.u-strasbg.fr
SIMBAD Astronomical Database: Results for NGC 6604 [online]. [cit. 2021-12-07]. Dostupné online. (anglicky)
web.archive.org
FROMMERT, Hartmut. Revised NGC Data for NGC 6604 [online]. SEDS.org [cit. 2021-12-07]. Dostupné v archivu pořízeném dne 2021-02-27. (anglicky)