1. U.A Celmins, On cubic graphs that do not have an edge 3-coloring, Ph.D. Thesis, University of Waterloo, 1984.
2. L. Goddyn, Cycle covers of graphs, Ph.D. Thesis, University of Waterloo, 1988.
3. R. Häggkvist, K. Markström, Cycle double covers and spanning minors, Technical Report 07, Department of Mathematics, Umeå University, Sweden, J. Combin. Theory Ser. B 96 (2) (2001) 183–206.
4. R. Häggkvist, S. McGuinness, Double covers of cubic graphs with oddness 4, Technical Report 2, Department of Mathematics, Umeå University, Sweden, 2000.
5. A. Huck, On cycle-double covers of graphs of small oddness, Discrete Math. 229 (1–3) (2001) 125–165, Combin. Graph Theory, Algorithms Appl.