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

Reference:

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

Suggested BibTeX entry:

@article{bibdb-export-pkaski-2008-27,
    author = {Petteri Kaski and Patric R. J. {\"O}sterg{\aa}rd and Svetlana Topalova and Rosen Zlatarski},
    journal = {Discrete Mathematics},
    number = {13},
    pages = {2732--2741},
    title = {Steiner triple systems of order 19 and 21 with subsystems of order 7},
    volume = {308},
    year = {2008},
}