Conclusions of research by R.A. Martin et al. published in 1983 in the Journal of Personality and Social Psychology under the title 'Sense of humor as a moderator of the relation between stressors and moods' and referred to by Debra Waterhouse in her book 'From Tired to Inspired'
Dale Carnegie (1888-1955)
Debra Waterhouse in her book 'From Tired to Inspired' published in 2001