Wilkens, H. (1980). The natural double sequence of globular clusters.
Cita Chicago Style (17a ed.)Wilkens, Herbert. The Natural Double Sequence of Globular Clusters. 1980.
Cita MLA (8a ed.)Wilkens, Herbert. The Natural Double Sequence of Globular Clusters. 1980.
Precaución: Estas citas no son 100% exactas.