Winter, Fabian Max Planck Institute for Research on Collective Goods, Max Planck Society;
http://dx.doi.org/10.1037/xge0000422 (Any fulltext)
Franzen, A., Mader, S., & Winter, F. (2018). Contagious Yawning, Empathy, and Their Relation to Prosocial Behavior. Journal of Experimental Psychology: General, 147(12), 1950-1958.