References

http://www.scena.org/lsm/sm4-1/sm4-1VoiceDoc_en.htm - Comfortable Vocal Ranges

http://cnx.org/content/m11716/latest/ - HPS

http://cnx.org/content/m11714/latest/ - HPS

http://web.media.mit.edu/~moo/thesis/YEK_thesis.pdf - Singing Voices Analysis/Synthesis (Thesis)

http://www.phys.unsw.edu.au/jw/notes.html - Musical Scale