A great overview of research behind and reasons for micro-credentials:
http://digitalpromise.org/wp-content/uploads/2016/06/Microcredentials_Driving_teacher_learning_leadership.pdf

The major momentum behind micro-credentials

Micro-credentials Guide Assessment for Learning in Rhode Island
http://cce.org/thought-leadership/blog/post/micro-credentials-guide-assessment-for-learning-in-rhode-island By Justin Paley and Gary Chapin July 28, 2016

Digital Promise: Micro-credentials-Driving Teacher Learning and Leadership
http://digitalpromise.org/wp-content/uploads/2016/06/Microcredentials_Driving_teacher_learning_leadership.pdf

Hewlett Foundation: Developing a System of Micro-Credentials
http://www.hewlett.org/wp-content/uploads/2016/08/mc_deeperlearning.pdf