@article{
    Kaski05b,
    author = "Kaski, Petteri",
    note = "Proceedings of {ALCOMA05}, {A}pril 3--10, {T}hurnau, {G}ermany",
    title = "Nonexistence of perfect {S}teiner triple systems of orders 19 and 21",
    url = "http://www.tcs.hut.fi/~pkaski/perfsts.ps",
    journal = "Bayreuther Mathematische Schriften",
    volume = "74",
    year = "2005",
    pages = "130--135"
}