Books on Yantras

[Raoul Martens]

An obvious suggestion:

Ernest G. McClain: The Myth of Invariance; The Origin of Gods, Mathematics
and Music from the Rg Veda to Plato, Shambala Publications Inc. 1123 Spruce
Street, Boulder, Colorado 80302. Distributed in the United States by Random
House, in Canada by Random House of Canada Ltd and in the Commonwealth by
Kegan Paul Ltd., London and Henly-on-Thames.

Sincerely R. Martens