Lundmark, K. E. (1920). The relations of the globular clusters and spiral nebulæ to the stellar system: An attempt to estimate their parallaxes. Almqvist & Wiksells boktryckeri-a.-b..
Chicago-referens (17:e uppl.)Lundmark, Knut Emil. The Relations of the Globular Clusters and Spiral Nebulæ to the Stellar System: An Attempt to Estimate Their Parallaxes. Stockholm: Almqvist & Wiksells boktryckeri-a.-b., 1920.
MLA-referens (8:e uppl.)Lundmark, Knut Emil. The Relations of the Globular Clusters and Spiral Nebulæ to the Stellar System: An Attempt to Estimate Their Parallaxes. Almqvist & Wiksells boktryckeri-a.-b., 1920.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.