Isaev, Alexander2020-12-202020-12-201050-6926http://hdl.handle.net/1885/217999In our joint article with N. Kruzhilin of 2002, we showed that every connected complex manifold of dimension n ≥ 2 that admits an effective transitive action by holomorphic transformations of the unitary group Un is biholomorphic to the quotient of a Hopf manifold by the action of Zm for some integer m satisfying (n,m) = 1. In this note, we complement the above result with an explicit description of all effective transitive actions of Un on such quotients, which provides an answer to a 10-year-old question.application/pdfen-AU201710.1007/s12220-016-9744-52020-11-23