Feng, Fan. “The Effects of Tianjin’s Openness on Economic Development in Beijing-Tianjin-Hebei Region Based on Extended Solow Model”. International Journal of Economics and Financial Issues 6, no. 3 (July 23, 2016): 1151–1154. Accessed April 23, 2024. https://www.econjournals.com/index.php/ijefi/article/view/2389.