Jim Fultz

Empathy, Sadness, and Distress Three Related but Distinct Vicarious Affective Responses to Another's Suffering

Mark Schaller, R. Cialdini, M. Schaller, 1988, Personality & social psychology bulletin.

Influence of self-reported distress and empathy on egoistic versus altruistic motivation to help.

Karen O'Quin, C. Daniel Batson, A. Isen, 1983 .

Empathy-based helping: is it selflessly or selfishly motivated?

Robert B. Cialdini, Mark Schaller, A. L. Beaman, 1987, Journal of personality and social psychology.