The Mathematical Society of South Eastern Europe (MASSEE) was established on 1st March 2003. 

The registered office of MASSEE is hosted by the Hellenic Mathematical Society in Athens, Greece at 34, Panepistimiou (Eleftheriou Venizelou) Street, GR. 106 79 – Athens, Greece. The main scope of the Association is to develop cooperation between and beyond the communities that are involved and further collaborate for adding value to the common activities organized in the area with main purpose the advancement of mathematics research and education.

For more information here.