Here is Lawrence Jr in the Social Security Death Index:
Name: Lawrence Bertelson
Last Residence: 07928 Chatham, Morris, New Jersey, United States of America
Born: 18 Apr 1914
Died: Feb 1983
State (Year) SSN issued: New Jersey (Before 1951)
Gordon Bertelson is listed in the 1957 and 1959 Morristown, New Jersey directories.
He may still be living as he is not in the SSDI.