1. The intersection problem for combinatorial designs;Billington;Congr. Numer.,1993
2. Combinatorial trades: a survey of recent results;Billington,2003
3. The complete classification of the triad systems in fifteen elements;Cole;Mem. Natl. Acad. Sci.,1917
4. The theory of trade-off for t-designs;Hedayat;IMA Vol. Math. Appl.,1990
5. Disjoint paths in graphs;Seymour;Discrete Math.,1980