In 1950, he refused to sign a special loyalty oath imposed on the faculty by the University of California's Board of Regents; for this reason he and a number of other professors were fired.

Please remove spaces between words.
In1950,herefusedtosignaspecialloyaltyoathimposedonthefacultybytheUniversityofCalifornia'sBoardofRegents;forthisreasonheandanumberofotherprofessorswerefired.