Links

www.harmonicwhirlies.com 
(musical instruments created and manufactured by Sarah Hopkins)

www.australianmusiccentre.com.au/artists/hopkins-sarah

http://www.mortonmusic.com/news-and-messages.aspx 
(Sarah's choral music publishers)

www.annenorman.com 
(Anne Norman, shakuhachi player and composer)

www.margaretbrandman.com 
(Margaret Brandman, composer and music educator)

www.tranquanghai.com 
(harmonic overtone singing)