1. Allibone, T.E. and Saunderson, J.C. (1981). Discharge characteristics of sphere and rod gaps stressed with d.c. voltages. 15th International Conference on Phenomena in Ionized Gases, Minsk, USSR.
2. Colombo, A, Mosca, W. and Motta, G. (1972). The performance of sphere and rod gap under high d.c. voltages. Proc. IEEE PAS-91, 501–509.
3. Feser, K. (1980). A measuring spark-gap for high d.c. voltages. CIGRE Committee 33 (WG 03) Paper 28.
4. Point discharge from natural and artificial points;Maund;Quarterly Jnl. R. Met. Soc,1960
5. Peschke, E. (1968). Der durch und uberschlag bei hoher gleichspannung in luft Diss, T.H., Muchen.