Yongwu, Zheng, zhang chongcong, and Zhang Jian. “The Coordinated Development of Beijing-Tianjing-Hebei Urban Research”. Advances in Social Sciences Research Journal 2, no. 12 (December 28, 2015). Accessed November 22, 2024. http://116.203.177.230/index.php/ASSRJ/article/view/1721.