* Austria: Erwin Schroeder Institut fuer Theoretische Physik (Vienna). 

* Brazil: Universidade de São Paulo, São Paulo;

Instituto de Matemática Pura e Aplicada (IMPA), Rio de Janeiro;

Pontifícia Universidade Católica do Rio de Janeiro,

Rio de Janeiro; Universidade Federal do Ceará, Fortaleza;

Universidade Federal de Goias, Goiana; Universidade Estadual

de Campinas, Campinas; Universidade Federal de São Carlos,

São Carlos.

* Canada: Dalhousie University, Halifax; Université de

Montréal, Montréal; Queen's University, Kingston; York

University, Toronto; University of Waterloo; University of

Calgary; University of British Columbia, Vancouver;

Université de Québec, Montreal; Université Laval, Québec;

McGill University, Montreal; Université d'Ottawa, Ottawa;

Memorial Universityty of Newfoundland, Corner Brook;

Memorial Universityty of Newfoundland, St.John's.

* China: Peking Universityty, Beijing; Fudan University,

Shanghai.

* France: Université de Montpellier;

Université des Sciences et Techniques de Lille.

* Germany: Universität Heidelberg; Universität Konstanz;

Universität München; Max Planck Institut für Mathematik, Bonn.

* Great Britain: Oxford University; University of Manchester;

University of Edinburg; University of Aberdeen; Cambridge University.

* Italy: Università di Genova; Università di Firenze;

Università di Milano; Canadian Academic Centre in Italy, Rome;

Convegno Italiano di Topologia, Sorrento; Scuola Matemetica

Interuniversitaria, Perugia; Gruppo Italiano di Topologia,

Acquasparta; Accademia Peloritana dei Pericolanti, Messina;

Università di Messina; Università di Napoli; Politecnico di

Milano; Università di Lecce; Università Cattolica di Brescia;

Università di Trieste.

* Japan: Shimane University, Matsue; Musashe Institute of

Technology, Tokyo; Tokyo University; Kyoto University.

* Spain: Universidad Autonoma de Barcelona.

* USA: University of Chicago; Rutgers University, New Brunswick;

University of Wisconsin-Parkside, Kenosha; University of Rochester.

* USSR: Steklov Institute of Mathematics, Moscow;

Moscow State University; Ukranian Academy of Science, Lvov.

* Switzerland: Eidgenössische Technische Hochschule, Zürich.