There he visited the Institute for Advanced Study for a year or so, then taught at the University of Kansas and at the University of Colorado, before settling at Penn State in 1963, where he remained until his retirement in 1976.
There he visited the Institute for Advanced Study until the fall of 1949, then taught at the University of Kansas in Lawrence until moving to the University of Colorado in 1952. He moved to Penn State in 1963 as a research professor, where he remained until his retirement in 1976.