The, N. D., D. T. M. Dung, A. Ahmed, P. T. Ha, S.- ur Rehman, N. T. Son, and K. H. Giang. “Combining Sonic While Drilling and Formation Pressure While Drilling for Pore Pressure Analysis to Reduce Drilling Risk: A Case Study in Offshore Vietnam”. Petrovietnam Journal, Vol. 6, June 2016, pp. 20-27, http://www.pvj.com.vn/index.php/TCDK/article/view/522.