1949-51 Teaching Assistant, Columbia University
1951-53 RCA Fellow, Columbia
1953-55 Research Associate, Stanford University
1957 Visiting Scientist, Bell Laboratories,Murray Hill (Summer)
1955-59 Assistant Professor, University ofMinnesota
1959-62 Associate Professor, University ofMinnesota
1962-63 Professor, University of Minnesota
1963-2000 Professor, University of Michigan
2000- Professor Emeritus, University of Michigan