Annapurna Devi, N., et al. “Production and Evaluation of Biodiesel from Sunflower (Helianthus Annus) and Nigerseed Oil (Guizotia Abyssinica)”. Asian Journal of Chemistry, vol. 18, no. 4, Mar. 2010, pp. 2951-8, https://asianpubs.org/index.php/ajchem/article/view/20713.