Projective planes of order 12 and PG(3,3)
The author gives a complete proof of the fact that the projective space \(\text{PG}(3,3)\) cannot be extended to a projective plane of order~12. An incomplete proof (omitting some cases) was given by \textit{M. Hall} and \textit{R. Roth} [J. Comb. Theory, Ser. A 37, 22-31 (1984; Zbl 0543.05015)]. Actually, the author proves a slightly more general result, namely: There does not exist a covering set of spreads in \(\text{PG}(3,3)\).
scientific article; zbMATH DE number 1369803