Śliwak, Jacek, and Rafał P. Bartczuk. “Altruism/Non-Altruism Questionnaire – Short Version: The Revision of the Method Based on Bifactor Analysis”. Journal for Perspectives of Economic Political and Social Integration 29, no. 1 (December 18, 2023): 31–59. Accessed June 21, 2026. https://czasopisma.tnkul.pl/index.php/jpepsi/article/view/3824.