Geographical extension (1974): Correspondence with the International Association of Semiology on the organisation of its first congress (scheduled for August 1967, Warsaw, did not take place) and the International Association of Semiotics on the organisation of its first congress (2-6 June 1974, Milan)
Correspondence (1963) with CISS, ICSU, Union of International Associations, Coordinating Committee for International Volunteer Workcamps, SCHM, AIAP, CIM, ICOM, Standing Committee of NGOs
Correspondence (1966) with Union of International Associations, ICSU, CISS, NGO Standing Committee, International NGO Committee for the International Year of Human Rights, various
Correspondence (1968) with CIM, ICSU, CISS, Conference of International NGOs linked to UNESCO, Standing Committee of NGOs, International Conference of NGOs on Human Rights, AIU, ITI, AIAP, Union of International Associations, CIEPS, ICOM, World Federation of Twinned Cities, International Schools Association, Universala Esperanto Asocio
Correspondence (1970) with Union of International Associations, World Federation of United Nations Associations, ICSU, ICOM, CISS, Standing Committee of NGOs
Correspondence (1971) with Union of International Associations, World Federation of United Nations Associations, ICSU, ICOM, CISS, Standing Committee of NGOs, CIM
Correspondence (1978) with CIM, ICSU, International Catholic Centre for UNESCO, World Federation of Scientific Workers, African Mathematical Union, National Social Science Councils, Standing Committee of NGOs
Correspondence (1984) with ICSU, Union of International Associations, International Association of Universities, International Federation for Home Economics, International Association of Literary Critics, ICOM, NGO Standing Committee, World Confederation of Organizations of the Teaching Profession
Correspondence (1985) with CICT, Coordinating Committee for International Voluntary Service, ITI, ICSU, UOIF, Standing Committee of NGOs, Union of International Associations, IFSSO, ICOM, CISS, International Association of Legal Sciences
Correspondence (1987) with ICSU, NGO Standing Committee, World Federation of UNESCO Clubs and Associations, AAAST, ITI, AIAP, International Catholic Centre for UNESCO