2013-11-15 PDF of "OpenGL Shading Language Third Edition" Randi J.Rost, Bill Licea-Kane. http://deca.cuc.edu.cn/Community/cfs-filesystemfile.ashx/__key/CommunityServer.Components.PostAttachments/00.00.00.06.49/Addison.Wesley.OpenGL.Shading.Language.3rd.Edition.Jul.2009.pdf