http://crystalreceiver.co.uk/detectors.htm\\
http://bizarrelabs.com/crystal.htm\\
[[http://www.hpfriedrichs.com/radioroom/crystals/doc/crystals-of-crystal-radio-table1-2014-06-11.pdf|vhodne mineraly]]

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{{http://sites.coloradocollege.edu/ideaspace/files/2014/07/Radio-Rock-2.jpg}}\\
http://sites.coloradocollege.edu/ideaspace/2014/07/15/transmissionfrequency-tesla-and-his-legacy/