1. Pope A. (1978): In: Dynamic Properties of Glia Cells, edited by E. Schoffeniels, G. Franck, L. Hertz and D.B. Tower pp. 13–20. Pergamon, Oxford.
2. Ramon Y. and Cajal S. (1909): Histologie du Systeme Nerveux de l’Homme et des Vertebres vol. 1, p. 246. Paris.
3. Hyden H. (1959): Nature, 184: 433–435.
4. Tsien R.W. (1988): TINS, 11: 419–424.
5. Walz W. (1989): Prog. Neurobiol., 33: 309–333.