History and recipes are adapted from:

http://www.geocities.com/tpkamsin/fbonigiri/onigiri.html
http://www.autec-usa.com/services/about_onigirimachine.html
http://www.recipezaar.com/Basic-Onigiri-60398
http://tzk-web.com/kisara/pic/takana-onigiri.jpg