Klaus Gürlebeck, born 1954, Dr. rer. nat. 1984 Technische Hochschule Karl-Marx-Stadt (Chemnitz), Habilitation 1988 TU Karl-Marx-Stadt (Chemnitz), since 1999 Full Prof. Bauhaus-Universität Weimar; co-editor of several international mathematical journals; interested in quaternionic analysis, discrete function theories and applications to partial differential equations.Klaus Habetha, born 1932, Dr. rer. nat. 1959 Freie Universität Berlin, Habilitation 1962 Technische Universität Berlin, Prof. Technische Universität Berlin, Full Prof. Universität Dortmund and since 1975 RWTH Aachen, here Rector 1987 - 1997, vice-president of German Rectors Conference; co-editor of the journal Complex Variables and elliptic equations until 2007; interested in function theory for partial differential equation.Wolfgang Sprößig, born 1946 , Dr. rer. nat. 1974 Technische Hochschule Karl-Marx-Stadt (Chemnitz) Habilitation 1979 TU Chemnitz, Ass. Prof. TU Chemnitz, since 1986 Full Prof. TU Bergakademie Freiberg, Head of the Institute of Applied Analysis 1993 -2012. Since 1998 Editor-in-Chief of the journal Mathematical Methods in the Applied Sciences, co-editor of several international mathematical journals, interested in hypercomplex analysis and its applications.