Bernabé-Valero, G., García-Alandete, J., & Gallego-Pérez, J. F. (2013). Construction of a gratitude questionnaire: The Gratitude Question-naire–20 Items (G-20). Anales De Psicología Annals of Psychology, 30(1), 278–286. https://doi.org/10.6018/analesps.30.1.135511