01070nam a2200277 i 450099100087996970753620020507175122.0930605s1989 us ||| | eng 0821851039b10770197-39ule_instLE01303736ExLDip.to MatematicaengAMS 05C15Appel, Kenneth I.222857Every planar map is four colorable /Kenneth Appel, Wolfgang HakenProvidence, R. I. :American Mathematical Society,1989xv, 741 p. ;25 cmContemporary mathematics,0271-4132 ;98Four-color problemHaken, Wolfgangauthorhttp://id.loc.gov/vocabulary/relators/aut54072.b1077019723-02-1728-06-02991000879969707536LE013 05C APP11 (1989)12013000128818le013-E0.00-l- 00000.i1086858628-06-02Every planar map is four colorable1455559UNISALENTOle01301-01-93ma -engus 01