1. A Kuratowski Theorem for the Projective Plane;Archdeacon,1980
2. 103 graphs that are irreducible for the projective plane;Glover;J. Combin. Theory Ser. B,1979
3. Ordering by divisibility in abstract algebras;Higman,1952
4. Counterexamples in the theory of well-quasi-ordered sets;Jenkyns,1969
5. Well-quasi-ordering, the tree theorem, and Vázsonyi's conjecture;Kruskal;Trans. Amer. Math. Soc.,1960