(Jagiellonian University, Poland)
was with us from may-2005 to april-2006
(Universidad Nacional del Nordeste, Argentina )
visited us during the months of October and November of 2004 and during the same period in 2006.
(Arak University, Iran)visited us during the months of September of 2006, August of 2007 and September of 2008
(Helsinki University, Finland)was with us during the 2005 year