1. Istituto Nazionale per lo Studio e la Cura dei Tumori -Milan (Italy)
2. Institut J. Paoli Calmettes - Marseilles (France)
3. Istituto Nacional de Cancer - Rio de Janeiro (Brazil)
4. Oncological Institute - Sofia (Bulgaria)
5. State Institute of Oncology - Budapest (Hungary)
6. Tulane University, School of Medicine - New Orleans (U.S.A.)
7. Institut Jules Bordet - Brussels (Belgium)
8. Oncological Institute - Brno (Czechoslovakia)
9. Sydney Hospital - Sydney (Australia)
10. Rotterdamsch Radio Therapeutische Instituut -Rotterdam (The Netherlands)
11. Oncological Institut - Cracow (Poland)
12. Hospital de Clinicas «M. Quintela» - Montevideo (Uruguay)
13. Het Neder-lands Kankeristituut - Amsterdam (The Netherlands)
14. Istituto di Oncologia - Genoa (Italy)
15. Institute of Oncology - Belgrade (Yugoslavia)
16. Cancer Research Centre of the U.S.S.R. Academy of Medical Sciences - Moscow (U.S.S.R.)
17. Petrov Research Institute of Oncology - Leningrad (U.S.S.R.)