J. Viljoen

On a penetrating radiation from thunderclouds

B. Schonland, J. Viljoen, 1933 .

XXXV. The distribution of the ionizing particles of the penetrating radiation in relation to the magnetic meridian

B. Schonland, J. Viljoen, 1933 .

Evidence of a Penetrating Radiation from Thunderstorms

J. Viljoen, B. F. J. SCHONLAND, 1932, Nature.

Possible anomalous behavior of the sound velocity in a magnetic crystal

R. H. Lemmer, J. Viljoen, 1977 .