1. The force exerted by the stellar system in the direction perpendicular to the galactic plane and some related problems;Oort;Bull. Astron. Inst. Netherlands,1932
2. Globular clusters, III. An analysis of the cluster radial velocities;Kinman;MNRAS,1959
3. The rotation of the Andromeda nebula;Babcock;Lick Observatory Bull.,1939
4. Intergalactic matter and the galaxy;Kahn;ApJ,1959
5. Rotation and density distribution of the Andromeda nebula derived from observations of the 21 cm line;van de Hulst;Bull. Astron. Inst. Netherlands,1957