1. M. Gawliński, personal communication.
2. W.A. Belyij, L.S. Pinčuk, Vvedenije v materialovedenije germetizirujuščich sistem, Nauka i Technika, Minsk, 1980.
3. J.A. Cross, Electrostatics: Principles, Problems and Applications, Hilger, Bristol, 1987.