Inverse and Improperly Posed Problems in Differential Equations : Proceedings of the Conference on Mathematical and Numerical Methods held in Halle, Saale (GDR) from May 29 to June 2, 1979
Monatsberichte der Deutschen Akademie de Wissenschaften zu Berlin : Mitteilungen aus Mathematik, Naturwissenschaft, Medizin und Technik. . Band 13, Heft 10-12