2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/58939A classification theorem is given of projective threefolds that are covered by a two-dimensional family of lines, but not by a higher dimensional family.LaTeX 2.09, 25 pagesAlgebraic Geometry14J30, 14J70, 14M07, 14N05text