Nguyen, N., T. Dao, T. Le, and C. Le. “Using Unmanned Aerial Vehicles (UAV) for Mornitoring the Construction Progress of Ho Chi Minh City Urban Railway Project”. Science and Technology Development Journal, Vol. 18, no. 2, June 2015, pp. 104-12, doi:https://doi.org/10.32508/stdj.v18i2.1064.