Todorov, Vasil, Vencislava Stoyanova, Kalina Pekova, Nikolay Kalaydzhiev, Desislava Bogdanova, and Ivan Milanov. “Headache Regisitries – Significance and Guidance for Their Development”. Cephalgia 26, no. 1 (December 30, 2024): 17–23. Accessed October 14, 2026. https://cephalgia.org/index.php/ce/article/view/68.