Phương, Nguyễn. “VỀ ĐÁ VÔI TRẮNG KHU VỰC LỤC YÊN - YÊN BÁI”. Vietnam Journal of Earth Sciences 27, no. 2 (March 27, 2005): 150–154. Accessed May 8, 2024. https://vjs.ac.vn/index.php/jse/article/view/9407.