54. Definition. For the purposes of this Chapter, unless the context otherwise requires, the expression" owner of copyright" shall include-
an exclusive licensee;
in the case of an anonymous or pseudonymous literary, dramatic, musical or artistic work, the publisher of the work, until the identity of the author or, in the case of an anonymous work of joint authorship, or a work of joint authorship published under names all of which are pseudonyms, the identity of any of the authors, is disclosed publicly by the author and the publisher or is otherwise established to the satisfaction of the Copyright Board by that author or his legal representatives.