1. Brahana, Henry; Systems of circuits on two-dimensional manifolds, Ann. of Math. (2) 23, 144–168 (1921).
2. Dehn, M.& Heegaard, P.; Analysis situs, in Enzyklop. d. math. Wissensch. III1, 153–220 (1907).
3. Francis, George; A topological picturebook, Springer 1990.
4. Ghys, Étienne; A singular mathematical promenade, ENS Éditions 2017. http://perso.ens-lyon.fr/ghys/promenade/
5. Markov Jr., Andrei; The insolubility of the problem of homeomorphy, Proc. International Congress of Mathematicians in Edinburgh, S. 300–306, Cambridge Univ. Press 1958.