%0 Journal Article
%A G. Koester
%T 4-critical 4-valent planar graphs constructed with crowns.
%J Mathematica Scandinavica
%D 1990
%P 15-22
%V 67
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MS2_1990__67_2_167117/
%F MS2_1990__67_2_167117