Riyanto O, Abdullah MH, Setyono G. 2⁴ Factorial Design Optimization of Process Variables for Biodiesel Production from Waste Cooking Oil. Eng. Technol. Appl. Sci. Res. [Internet]. 2026 Apr. 4 [cited 2026 Apr. 17];16(2):33228-32. Available from: https://mail.etasr.com/index.php/ETASR/article/view/15231