1. Affolter, H.: Pressure characteristics of reflux esophagitis. Helv. med. Acta 33, 395–402 (1966)
2. Benz, J. L., Hootkin, L. A., Margulies, S., Donner, M. W., Cauthorne, R. T., Hendrix, T. R.: A comparison of clinical measurements of gastroesophageal reflux. Gastroenterology 62, 1–5 (1972)
3. Bernstein, L. M., Baker, L. A.: A clinical test for esophagitis. Gastroenterology 34, 760–781 (1958)
4. Butterfield, D. G., Struthers, J. E., Showalter, J. P.: A test of gastroesophageal sphincter competence. The common cavity test. Amer. J. dig. Dis. 17, 415–421 (1972)
5. Code, C. F., Creamer, B., Schlegel, J., Olsen, A. M., Donoghue, F. E., Andersen, H. A.: An atlas of esophageal motility in health and disease. Springfield, Ill.: Ch. C. Thomas 1958