1. DuBois-Reymond, E. Untersuchungen uber tierische Elektrizitat, Berlin. 1848.
2. Galeotti, G. Concerning the E.M.F. which is generated at the surface of animal membranes on contact with different electrolytes. Zellforsh Phys Chem 1904; 49: 542–562.
3. Ussing, HH, Zerahn, K. Active transport of sodium as the source of electric current in the short-circuited isolated frog skin. Acta Physiologica Scandinavica 1951; 23:110–127.
4. Skou, JC. Enzymatic basis for active transport of Na+ and K+ across cell membrane. Physiol Rev 1965; 45:596–617.
5. Frizzell, RA, Field, M and Schultz, SG. Sodium-coupled chloride transport by epithelial tissues. Am J Physiol 1979; 236: F1–F8.