Steiner triple systems of order 19 and 21 with subsystems of order 7

Petteri Kaski, Patric R. J. Östergård, Svetlana Topalova, Rosen Zlatarski. Steiner triple systems of order 19 and 21 with subsystems of order 7. Discrete Mathematics, 308(13):2732-2741, 2008. [doi]

Abstract

Abstract is missing.