Liu, Huanxian, Ye Ran, Liang Dang, Ruirui Yang, Shuping Sun, Meichen Zhang, Ke Li, Chunfu Chen, Zhao Dong, and Shengyuan Yu. “Clinical Features and Outcomes of New Daily Persistent Headache in Patients in China and Comparison With Medication Overuse Headache: A Double-Center Retrospective Study”. Pain medicine 6, no. 1 (April 29, 2021): 10–20. Accessed June 21, 2021.