Thang, T. V., D. V. Thuan, V. N. Trinh, N. D. Khanh, B. D. Khanh, and N. T. Huong. “Constructing a Database and Software for Domestic Petroleum Contract Management ”. Petrovietnam Journal, Vol. 5, May 2015, pp. 66-72, http://www.tapchidaukhi.com/index.php/TCDK/article/view/462.