RT Journal Article SR Electronic T1 Headache of Gastro-Intestinal Origin JF Cleveland Clinic Journal of Medicine JO Cleve Clin J Med FD Cleveland Clinic SP 55 OP 58 VO 2 IS 3 A1 Hartsock, C. L. YR 1935 UL http://www.ccjm.org/content/2/3/55.abstract AB