IMPA (every summer since 1989) (IMPA)

International Centre for Theorerical Physics (ICTP) :

Septembre 1989,  March - August, 1992.  September  1995,  August  1, 1998 - November 16,  1998, August 2003

Universidad de Buenos Aires (Argentina) (UBA) : October 1993, October 1994.

Universidad Federal de Goias (Goiania, Brazil) (Dept. of Math.)  :
February, 1990 and December 1994.
 

Instituto de Matemáticas y Ciencias Afines--IMCA-- (Lima, Perú) (IMCA)
October, 2000.
 

Escuela Politécnica de Quito, Ecuador, October, 2010.