Triptan non-response in specialized headache care: cross-sectional data from the DMKG Headache Registry - Ruscheweyh, R; Gossrau, G; Dresler, T; Freilinger, T; Förderreuther, S; Gaul, C; Kraya, T; Neeb, L; Ruschil, V; Straube, A; Scheidt, J; Jürgens, T P (J Headache Pain, 2023)