The LSW-MPE-INAOE project for optical identification of a complete sample of northern ROSAT survey sources: status report - Thiering, Ingeborg; Krautter, Joachim; Appenzeller, Immo; Kneer, Reinhold (Abstracts of contributed talks and posters presented at the Joint Scientific Fall Meeting of the Astronomische Gesellschaft and of the Arbeitsgemeinschaft Extraterrestrische Forschung (AEF/DPG) at Bonn, 1995)