Official websites use .gov A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Written in the year of his retirement after twenty-seven years at Columbia University, this letter expressed Heidelberger's thoughts on the policy of mandatory retirement of university professors and on research opportunities for older scientists.