George, Jennifer M.; Bettenhausen, Kenneth

Understanding prosocial behavior, sales performance, and turnover: A group-level analysis in a service context.

Journal of Applied Psychology, Vol 75(6), Dec 1990, 698-709.

George, J. M. (1991).

State or trait: the effects of positive mood on prosocial behaviors at work.

Journal of Applied Psychology, 76, 299–307.