Validation and Test–Retest Reliability of the Cervicogenic Headache Severity Questionnaire (CeH-SeQ): A Patient-Reported Assessment ToolPrachi Choksi and Ankurkumar Premjibhai KhantEPJ Web Conf., 348 (2026) 01004DOI: https://doi.org/10.1051/epjconf/202634801004