Selected exercises by Craig Fraedrich - http://craigfraedrichmusic.com/

Selected exercises by Eric Bolvin - http://www.bolvinmusic.com

Selected exercises by Jay Lichtmann - http://uhaweb.hartford.edu/lichtmann/

Cover art designed by Yacu Malik - http://www.artofyacu.com/

French language (iPhone only) traslation by Akoya-Dev - http://akoya-dev.com/

Spanish language (iPhone only) translation by Victor Floresmeyer - http://grupohmv.com.mx