M. C. . Dávila de León and F. Chacón Fuertes, “Prediction of Longevity of Volunteer Service: A Basic Alternative Proposal”, Span. j. psychol., vol. 10, no. 1, pp. 115–121, May 2007, Accessed: Dec. 06, 2025. Available: https://revistas.ucm.es/index.php/SJOP/article/view/SJOP0707120115A