Die allumfassende Liebe, ihr Symbol der Zirkel

Geestelijke waarden der vrijmetselarij. Deel III. De meester

Life symbols : A brief study into the origin and significance of certain symbols which have been found in all civilisations, such as the cross, the circle, the serpent, the triangle, the tree of life, the swastika, and other solar emblems, showing the unity and simplicity of thought underlying their use as religious symbols

The ritual origin of geometry

Hergé chez les initiés

Via Lucis : De weg naar het Licht, Maçonnieke symbolen in het mausoleum van Jan Amos Comenius te Naarden

Sprankelende symbolen