7Emmous RA, McCullough ME. Counting blessing versus burdens: An experimental investigation of gratitude and subjective well-being in daily life. Journal of Personality and Social Psychology, 2003, 84:377-389.
8Watkins PS, Jason O, Melinda K, Russell. The debt of gratitude: Dissociating gratitude and indebtedness. Cognition and Emotion, 2006, 20(2): 214-241.
9McCullough ME, Emmons RA, Tsang J. The grateful disposition: A conceptual and empirical topography. Journal of Personality and Social Psychology, 2002, 82(1): 112-127.
10Adler MG, Fagley NS. Appreciation Individual differences in finding value and meaning as a unique predictor of subjective well-being. Journal of Personality, 2005, 73(2): 79- 514.