Thi Lan Anh, N., Thi Mai Hanh, N., Thi Thuy Dung, D. and Linh Chi, N. 2017. National oil companies in relationship with the states. Petrovietnam Journal. 2, (Feb. 2017), 54 - 61. DOI:https://doi.org/10.25073/petrovietnam journal.v2i0.129.