Thong-Innatra, K.; Theeraraj, G.; Yuwaree, C.; Charmondusit, K.; Hutacharoen, R. A Study of Biodiesel (Ethyl Ester) Production from Grease/Oil Rich Sludge through Acid-Catalytic Ethanol Transesterification and It’s Fuel Specifications. Environ. Nat. Resour. J. 2017, 8, 31-46.