Chronic Daily HeadacheNeurol 42:32-36, Sheftell,F.D., 1992
Chronic Daily HeadacheNEJM 354:158-165, Dodick,D.W., 2006
HeadacheJNNP 57:134-143, Pearce,J.M.S., 1994
Diagnosing the Severe HeadacheNeurol 44:S6-S12, Dalessio,D.J., 1994