Imre Lakatos
Donald W. Loveland
G. Hanna
Carsten Lund
M. Lerman
Wolfram Pohlers
Bruno Scarpellini
Conference on Computability in Europe (6th 2010 Ponta Delgada, Azores, Portugal)
ISILC Proof Theory Symposion University of Kiel 1974.
Rowan Garnier
Katalin Bimbo
Lev Dmitrievich Beklemishev
Danny De Schreye
Hutchison, David - undifferentiated
Wilfried Buchholz
Daniel Leivant
Michael Detlefsen