- International Clay Conference (4)
- Heller, L. (Liselotte) (2)
- International Committee for the Study of Clays (2)
- International Union of Geological Sciences (2)
- Graff-Petersen, Poul (1)
- International Association for Clay Research. Gruppo italiano (1)
- Rosenqvist, Ivan Thoralf, 1916- (1)
- Sanchez, A. (1)
- Serratosa, J. M. (1)
- Sociedad Española de Arcillas (1)
- Spain. Ministerio de Educación y Ciencia (1)
- Weiss, Armin (1)