Minimal blocking sets of class \([h,k]\) with respect to the external lines to an elliptic quadric of \(\text{PG}(3,q)\), \(q \geq 5\) prime, are characterized.
Citation
Paola Biondi, Pia Maria Lo Re. On Blocking Sets of External Lines to a Quadric in \(PG(3,q), q\) Prime[J], Ars Combinatoria, Volume 085. 43-48. .