1. Coxeter, H.S.M.: Regular Polytopes, Preface, 1st edn, p. vii. Dover Publications, New York (1973)
2. Abbott, E. A.: Flatland: A Romance of Many Dimensions, Basil Blackwell, Oxford, 1884
3. M. Emmer, ed., Flatland, text Italian & English, with DVD film Flatland, animation, animation, original soundtrack E. Morricone, 24 m., Bollati Boringhieri, Torino, (2008)
4. in [1], p. 118
5. Wells, H.G.: The Time Machine. W. Heinemann, London (1895)