http://www.phy.hk/wiki/englishhtm/StatWave.htm[br][br]https://phet.colorado.edu/sims/html/normal-modes/latest/normal-modes_all.html[br][br]http://www.physicsbootcamp.org/normal-modes-of-a-string.html[br][br]http://www.physicsbootcamp.org/forced-oscillations-of-a-string.html