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. 2017-08-03]. Čís. 2, s. B1-B46. Dostupné online. Bibcode1931AnLun...2....1C. (anglicky)
hubblesite.org
The Trifid Nebula: Stellar Sibling Rivalry [online]. NASA a Jeff Hester (Arizona State University), 1999-11-09 [cit. 2017-08-04]. Dostupné online. (anglicky)
seds.org
messier.seds.org
SEDS.org: Messier 20 [online]. [cit. 2017-08-03]. Dostupné online. (anglicky)
u-strasbg.fr
simbad.u-strasbg.fr
SIMBAD Astronomical Database: Results for M 20 [online]. [cit. 2017-08-03]. Dostupné online. (anglicky)