Career
In this position, he played a crucial role in the return of Icelandic manuscripts to Iceland from Denmark, representing Iceland in negotiations with the Danish authorities from 1972-1986. Jónas was a teacher at the Samvinnuskóli from 1952-1955, archivist at the National Archives of Iceland from 1957-1963, and the director of the Árni Magnússon Institute for Icelandic Studies from 1972-1994 (from which position he retired upon reaching the age limit). He spent 1978-1979 in the United Kingdom.