http://general-terms.thesaurus.ekt.gr/vocabhttp://general-terms.thesaurus.ekt.gr/vocab?tema=9029electromagnetic waves http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 magnetic fields RT http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 electromagnetism RT http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 X-rays NT http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 gamma rays NT http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 light NT http://general-terms.thesaurus.ekt.gr/vocab?tema=9029 waves BT