บรรณานุกรม
http://club.myfri3nd.com/pianoplaying/webboard/35/104/
http://www.piano-ohyes.com/lessons/piano-types.html
http://th.wikipedia.org/wiki/%E0%B9%80%E0%B8%9B%E0%B8%B5%E0%B8%A2%E0%B9%82%E0%B8%99
