Ruch, Willibald; Hofmann, Jennifer (2014). Factor analysis of humor items. In: Attardo, Salvatore. Encyclopedia of Humor Studies. Thousand Oaks: SAGE, 227-228.
Ruch, Willibald; McGhee, Paul E (2014). Humor intervention programs. In: Schueller, S M; Parks, A C. Handbook of Positive Psychological Interventions. Oxford: Wiley-Blackwell, 179-193.