http://ithaki.lb.teiath.gr/tematres/vocab2/http://ithaki.lb.teiath.gr/tematres/vocab2/?tema=559ισοδυναμη εννοια https://el.wikipedia.org/wiki/%CE%9A%CE%B1%CF%84%CE%B7%CE%B3%CE%BF%CF%81%CE%AF%CE%B1:%CE%A3%CF%89%CE%BC%CE%B1%CF%84%CE%B9%CE%BA%CE%AE_%CE%AC%CF%83%CE%BA%CE%B7%CF%83%CE%B7