Houchens, G.W., Hurt, J., Stobaugh, R. and Keedy, J.L. 2012. Double-loop Learning: A Coaching Protocol for Enhancing Principal Instructional Leadership. Qualitative Research in Education. 1, 2 (Oct. 2012), 135–178. DOI:https://doi.org/10.4471/qre.2012.08.