Binay K. Bhattacharya Jurek Czyzowicz Peter Egyed Ivan Stojmenovic Godfried T. Toussaint Jorge Urrutia Computing Shortest Transversals of Sets (Extended Abstract). 71-80 1991 Symposium on Computational Geometry http://doi.acm.org/10.1145/109648.109656 db/conf/compgeom/compgeom91.html#BhattacharyaCESTU91