Giraldo, L., A. Gracia, and E. do Amaral. “Willingness to Pay for Biodiesel in Spain: A Pilot Study for Diesel Consumers”. Spanish Journal of Agricultural Research 8, no. 4 (1): 887-894. Accessed February 23, 2025. https://sjar.revistas.csic.es/index.php/sjar/article/view/1382.