B. Alspach, L. Goddyn and C.-Q. Zhang, Graphs with the circuit cover property, Trans. Amer. Math. Soc. 344, 131-154, 1994.
August 27, 1997. Tommy R. Jensen
C. Thomassen, Grötzsch's 3-Color Theorem and its Counterparts for the Torus and the Projective Plane, J. Combin. Theory Ser. B 62, 268-279, 1994.
August 13, 1997. Tommy R. Jensen
D.A. Youngs, Minimal orientations of colour critical graphs, Combinatorica 15, 289-295, 1995.
August 7, 1997. Tommy R. Jensen