1. Abrahams, A. (1954). In Melaenci. French's Index of Differential Diagnosis, 7th ed., edited by A. H. Douthwaite, pp. 468-469. Wright, Bristol.
2. Avery Jones, F., and Gummer, J. W. P. (1960). Clinical Gastroenterology, p. 288. Blackwell, Oxford.
3. Chemical Methods in Clinical Medicine;Harrison, G.A.,1957
4. The color of blood-containing feces following the instillation of citrated blood at various levels of the small intestine;Hilsman, J.H.;Gastroenterology,1950
5. Observations on the oral administration of citrated blood in. man;Schiff, L.; Stevens, R.J.; Shapiro, N.; Goodman, S.;Amer. J. med. Sci,1942