Preuss N.O. (2001) Hans Christian Cornelius Mortensen: Aspects of his life and of the history of bird ringing. ARDEA 89 (1): 1-6

A brief description of Hans Christian Cornelius Mortensen, the first to use individual numbered rings in the study of bird migration, with information of some aspects of the history of bird ringing. This paper is a slightly modified version of the opening lecture at the conference Bird Ringing 100 Years, Helgoland 1999