Schachner, A. “If Horses Entrain, don’t Entirely Reject Vocal Learning: An Experience-Based Vocal Learning Hypothesis”. Empirical Musicology Review, vol. 7, no. 3-4, July 2013, pp. 157-9, https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/EMR/article/view/3748.