Truong, N. N., and T. V. Nhac. “Determination of the Constant <i>W</i><sub>o</sub> For Local Geoid of Vietnam and it’s Systematic Deviation from the Global Geoid”. Vietnam Journal of Marine Science and Technology, vol. 17, no. 4B, Dec. 2017, pp. 138-44, doi:10.15625/1859-3097/17/4B/13001.