E. von Tschermak-Seysenegg, Austria (1956)
 J.C. Drost, The Netherlands (1959)
 W. Rudorf, Germany (1965)
 J. Bustarret, France (1968)
 E. Åkerberg, Sweden (1972)
 J.G. Hawkes, United Kingdom (1989) 
 J.S. Bojanowski, Poland (1989)
H. Hänsel, Austria (2004)
F. Nuez-Viñals, Spain (2004)
G. Röbbelen, Germany (2004)