1. Krieger, D.T. (1986). An overview of neuropeptides. In: Neuropeptides in Neurologic and Psychiatric Diseases, eds., J.B. Martin and J.D. Barchas, Raven Press, New York, 1–32
2. Mutt, V. (1982). Gastrointestinal hormones: a field of increasing complexity. Scand. J. Gastroenterol. (suppl), 77, 133–152
3. Bayliss, W.M. and Starling, E.H. (1902). The mechanism of pancreatic secretion. J. Physiol., 28, 325–353
4. Pearse, A.G.E. (1976). Peptides in brain and intestine. Nature (London), 262, 92–94
5. Pearse, A.G.E. (1979). The APUD concept and its relationship to the neuropeptides. In: Brain Peptides: A New Endocrinology, eds., A.M. Gotto Jr., E.J. Peck Jr. and A.E. Boyd III. Elsevier North-Holland, Amsterdam, 89–101