http://atheo.gr/%cf%84%ce%bf-%cf%86%cf%85%cf%83%ce%b9%ce%ba%cf%8c-%cf%80%ce%b5%cf%81%ce%b9%ce%b2%ce%ac%ce%bb%ce%bb%ce%bf%ce%bd-%cf%84%ce%b7%cf%82-%cf%89%ce%ba%ce%b5%ce%b1%ce%bd%ce%af%ce%b1%cf%82/
https://www.slideshare.net/ketiathana/ss-36713179
https://www.slideshare.net/4gym-glyfadas/5-16777833
http://atheo.gr/%ce%bf%ce%b9-%ce%ba%ce%ac%cf%84%ce%bf%ce%b9%ce%ba%ce%bf%ce%b9-%ce%ba%ce%b1%ce%b9-%cf%84%ce%b1-%ce%ba%cf%81%ce%ac%cf%84%ce%b7-%cf%84%ce%b7%cf%82-%cf%89%ce%ba%ce%b5%ce%b1%ce%bd%ce%af%ce%b1%cf%82/
https://www.slideshare.net/ketiathana/ss-36713179
https://www.slideshare.net/4gym-glyfadas/5-16777833
http://atheo.gr/%ce%bf%ce%b9-%ce%ba%ce%ac%cf%84%ce%bf%ce%b9%ce%ba%ce%bf%ce%b9-%ce%ba%ce%b1%ce%b9-%cf%84%ce%b1-%ce%ba%cf%81%ce%ac%cf%84%ce%b7-%cf%84%ce%b7%cf%82-%cf%89%ce%ba%ce%b5%ce%b1%ce%bd%ce%af%ce%b1%cf%82/