Fractional Colouring and Hadwiger's Conjecture

Every planar map is four colorable

K. I. Appel, Wolfgang Haken · Bulletin of the American Mathematical Society · 1976 · 1.1K citations · Full text

Natural Sciences, Architectural Representation, Color Theory +5

Every planar map is four colorable. Part I: Discharging

K. I. Appel, Wolfgang Haken · Illinois Journal of Mathematics · 1977 · 879 citations

Architecture, Architectural Representation, Descriptive Geometry +2

Every planar map is four colorable. Part II: Reducibility

K. I. Appel, Wolfgang Haken, J. Koch · Illinois Journal of Mathematics · 1977 · 710 citations · Full text

Computing, Computer Systems, Computer Graphics +2

The Four-Colour Theorem

Neil Robertson, Daniel P. Sanders, Paul Seymour et al. · Journal of Combinatorial Theory Series B · 1997 · 608 citations

An extremal function for contractions of graphs

Andrew Thomason · Mathematical Proceedings of the Cambridge Philosophical Society · 1984 · 330 citations

Natural Sciences, Mathematics, Combinatorics +6