Are you curious about the Geometry 3-Dimension and 4-Dimension Spaces as they relate to 3d-Puzzles?
The Digital Books are very easy to understand even with limited knowledge of basic geometry.
The Abridged PDF versions of each Book are now available: they do not include multimedia content such as videos, animations or quizzes.
Authors: Bernard & Pamela Cook Dreyer
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NOTE: Click here for the Multimedia versions of these Digital Books