[[1] Grzegorz Bancerek, Czesław Byliński, Adam Grabowski, Artur Korniłowicz, Roman Matuszewski, Adam Naumowicz, and Karol Pąk. The role of the Mizar Mathematical Library for interactive proof development in Mizar. Journal of Automated Reasoning, 61(1):9–32, 2018. doi:10.1007/s10817-017-9440-6.10.1007/s10817-017-9440-6604425130069070]Search in Google Scholar
[[2] Adam Grabowski, Artur Korniłowicz, and Adam Naumowicz. Four decades of Mizar. Journal of Automated Reasoning, 55(3):191–198, 2015. doi:10.1007/s10817-015-9345-1.10.1007/s10817-015-9345-1]Search in Google Scholar
[[3] Pavol Hell and Jaroslav Nesetril. Graphs and homomorphisms. Oxford Lecture Series in Mathematics and Its Applications; 28. Oxford University Press, Oxford, 2004. ISBN 0-19-852817-5.]Search in Google Scholar
[[4] Ulrich Knauer. Algebraic graph theory: morphisms, monoids and matrices, volume 41 of De Gruyter Studies in Mathematics. Walter de Gruyter, 2011.10.1515/9783110255096]Search in Google Scholar
[[5] Sebastian Koch. Underlying simple graphs. Formalized Mathematics, 27(3):237–259, 2019. doi:10.2478/forma-2019-0023.10.2478/forma-2019-0023]Search in Google Scholar
[[6] Gilbert Lee and Piotr Rudnicki. Alternative graph structures. Formalized Mathematics, 13(2):235–252, 2005.]Search in Google Scholar
[[7] Karol Pąk. The friendship theorem. Formalized Mathematics, 20(3):235–237, 2012. doi:10.2478/v10037-012-0028-7.10.2478/v10037-012-0028-7]Search in Google Scholar
[[8] Gunther Schmidt and Thomas Ströhlein. Relations and graphs: discrete mathematics for computer scientists. Springer Science & Business Media, 2012.]Search in Google Scholar
[[9] Yozo Toda. The formalization of simple graphs. Formalized Mathematics, 5(1):137–144, 1996.]Search in Google Scholar
[[10] Robin James Wilson. Introduction to Graph Theory. Oliver & Boyd, Edinburgh, 1972. ISBN 0-05-002534-1.]Search in Google Scholar
[[11] Edmund Woronowicz. Relations and their basic properties. Formalized Mathematics, 1 (1):73–83, 1990.]Search in Google Scholar
[[12] Edmund Woronowicz. Relations defined on sets. Formalized Mathematics, 1(1):181–186, 1990.]Search in Google Scholar