2017
September--October 2017 Arizona State University, Phoenix, USA
(exchange program).
2006
November--December 2006 Carlow Institute of Technology, Ireland
(study visit).
2002
2002 Institute "Alfred Renyi" of Hungarian Academy of Sciences,
Department of Mathematics and Applications
of the Central European University
(Doctorial School in Mathematics).
2002
March--May 2002 University of Jena, Germany
(study visit, seminary presentation).
2001
May--June 2001 University of La Rochelle, France
(seminary presentation).
1998
1997-1998 Moscow State University, Russia
(Phd thesis).