An Trung Nguyen, Thi Cam Ha Nguyen, Tien Thinh Lai, Hoang Giang Nguyen, Ha Vu, and Thanh Long Nguyen, “Developing a database for Cs-137 radioactivity concentration and assessing residual levels in surface soils of Quang Ninh, Hai Phong, and Lang Son provinces”, VJSTE, vol. 63, no. 3, pp. 92-96, Sep. 2021.