Are migraine and tension-type headache diagnostic types or points on a severity continuum? An exploration of the latent taxometric structure of headache.
Turner DP, Smitherman TA, Black AK, Penzien DB, Porter JAH, Lofland KR, Houle TT. Are migraine and tension-type headache diagnostic types or points on a severity continuum? An exploration of the latent taxometric structure of headache. Pain. 2015 Jul; 156(7):1200-1207.