Ha, Dao Thi Hai, Hoang Linh, and Luong Van Tuyen. 2013. “Synthesis of Pour Point Depressant Additives for Production and Transportation of High-Paraffin Bach Ho Crude Oil Based on Ester of Poly-Triethanolamine”. Petrovietnam Journal 5 (May), 26-35. http://www.pvj.vn/index.php/TCDK/article/view/662.