Epstein, L H The relationship between frontalis muscle activity and self-reports of headache pain. [electronic resource] - Behaviour research and therapy 1978 - 153-60 p. digital Publication Type: Journal Article ISSN: 0005-7967 Standard No.: 10.1016/0005-7967(78)90061-x doi Subjects--Topical Terms: AdultBiofeedback, PsychologyElectromyographyFacial Muscles--physiopathologyFemaleHeadache--physiopathologyHumansMiddle AgedMuscle Contraction