Hussien, Marwan, and Hayder Abdul hameed. “Biodiesel Production from Used Vegetable Oil (sunflower Cooking Oil) Using Eggshell As Bio Catalyst”. Iraqi Journal of Chemical and Petroleum Engineering, vol. 20, no. 4, Dec. 2019, pp. 21-25, https://doi.org/10.31699/IJCPE.2019.4.4.