Sources:

"A Better Grading System: Standards-Based, Student-Centered Assessment" by Jeanetta Jones Miller
(http://www.ncte.org/library/NCTEFiles/Resources/Journals/EJ/1031-sep2013...)

Joshua Bowman blogs about his experiences with standards based grading at Smith College.
http://thalestriangles.blogspot.com/2013/05/sbg-what-worked-well.html

"Systems and Achievement as Measured by the Colorado Student Assessment Program (CSAP)" by Kenneth G. Haptonstall (http://search.proquest.com/docview/89285714)