Celebratio Mathematica

K. Ap­pel and W. Haken: “The ex­ist­ence of un­avoid­able sets of geo­graph­ic­ally good con­fig­ur­a­tions,” Ill. J. Math. 20 : 2 (1976), pp. 218–​297. MR 392641 Zbl 0322.​05141 article

K. Ap­pel and W. Haken: “Every planar map is four col­or­able,” Bull. Am. Math. Soc. 82 : 5 (September 1976), pp. 711–​712. MR 424602 Zbl 0331.​05106 article

K. Ap­pel and W. Haken: “A proof of the four col­or the­or­em,” Dis­crete Math. 16 : 2 (October 1976), pp. 179–​180. MR 543791 Zbl 0339.​05109 article

K. Ap­pel and W. Haken: “Every planar map is four col­or­able, I: Dis­char­ging,” Ill. J. Math. 21 : 3 (1977), pp. 429–​490. A mi­crofiche sup­ple­ment to both parts was pub­lished in Ill. J. Math. 21:3 (1977). MR 543792 Zbl 0387.​05009 article

K. Ap­pel, W. Haken, and J. Koch: “Every planar map is four col­or­able, II: Re­du­cib­il­ity,” Ill. J. Math. 21 : 3 (1977), pp. 491–​567. A mi­crofiche sup­ple­ment to both parts was pub­lished in Ill. J. Math. 21:3 (1977). MR 543793 Zbl 0387.​05010 article

K. Ap­pel and W. Haken: “The solu­tion of the four-col­or-map prob­lem,” Sci. Amer. 237 : 4 (October 1977), pp. 108–​121. MR 543796 article

K. Ap­pel and W. Haken: “The four-col­or prob­lem,” pp. 153–​180 in Math­em­at­ics today: Twelve in­form­al es­says. Edi­ted by L. A. Steen. Spring­er (Ber­lin), 1978. incollection

K. Ap­pel and W. Haken: “An un­avoid­able set of con­fig­ur­a­tions in planar tri­an­gu­la­tions,” J. Comb. The­ory, Ser. B 26 : 1 (February 1979), pp. 1–​21. MR 525813 Zbl 0407.​05035 article

K. Ap­pel and W. Haken: “The four col­or proof suf­fices,” Math. In­tell. 8 : 1 (1986), pp. 10–​20. MR 823216 Zbl 0578.​05022 article

K. Ap­pel and W. Haken: Every planar map is four col­or­able. Con­tem­por­ary Math­em­at­ics 98. Amer­ic­an Math­em­at­ic­al So­ci­ety (Provid­ence, RI), 1989. With the col­lab­or­a­tion of J. Koch. MR 1025335 Zbl 0681.​05027 book