[1] Physics classroom, http://www.physicsclassroom.com/mmedia/waves/edl.html
[2] recognition system, http://www.allformp3.com/mp3-converter/mp3-wave-midi-converter.htm
[3] Digital Ear Real-Time, http://www.digital-ear.com/digital-ear/index.html
[4] IntelliScore, http://www.intelliscore.net/
[5] Guitar fundamental frequency, http://www5.ocn.ne.jp/~dgb/Tone_e.htm
[6] Phaneendra Rupanagudi Venkata, "Audio signal processing speech music discrimination," http://www.ece.arizona.edu/~arunu/DSP_Project.pdf
[7] Jeremy F. Alm and James S. Walker, "Time-frequency analysis of musical instruments," http://epubs.siam.org/sam-bin/getfile/SIREV/articles/38228.pdf