At the same time (starting in November 1948), he worked as an economist at the Organisation for Economic Co-operation and Development (OECD) until 1970, which was also the year when he obtained French citizenship.
Ao mesmo tempo, traballou como economista na Organización para a Cooperación Económica e o Desenvolvemento (OCED) ata 1970, o mesmo ano no que obtivo a cidadanía francesa.