Chen, Beiwen, Maarten Vansteenkiste, Wim Beyers, Liesbet Boone, Edward Deci, Jolene Kaap-Deeder, Bart Duriez, Willy Lens, Lennia Matos, Athanasios Mouratidis, Richard Ryan, Kennon Sheldon, Bart Soenens, Stijn Petegem, and Joke Verstuyf. 2015. “Basic Psychological Need Satisfaction, Need Frustration, and Need Strength across Four Cultures.” Motivation & Emotion 39(2):216-236.