Here you can find some useful links:

• Cyprus Mathematical Society, http://www.cms.org.cy
• Hellenic Mathematical Society, http://www.hms.gr
• Romanian Mathematical Society, http://rms.unibuc.ro/
• Bulgarian Mathematical Society, http://www.math.bas.bg/talents/
• Turkish Mathematical Society, http://www.tmd.org.tr/?lang=en
• Nesin Mathematics Village in Turkey, https://matematikkoyu.org/eng/