Algebraical and Topological Foundations of GeometryHans Freudenthal · First published 2014Open the Tome
Didactical phenomenology of mathematical structuresHans Freudenthal · First published 1899 · Latest edition 2006Open the Tome
The Concept and the Role of the Model in Mathematics and Natural and Social SciencesHans Freudenthal · First published 1961Open the Tome