José Miguel Díaz-Báñez Carlos Seara Joan Antoni Sellarès Jorge Urrutia Inmaculada Ventura Covering point sets with two convex objects. 179-182 2005 EWCG http://www.win.tue.nl/EWCG2005/Proceedings/46.pdf conf/ewcg/2005 db/conf/ewcg/ewcg2005.html#Diaz-BanezSSUV05