Florian Berger, Alexander Gilbers, Ansgar Grüne, Rolf Klein
How Many Lions Are Needed to Clear a Grid? Algorithms 2(3), pp. 1069-1086, 2009.
Alexander Gilbers, Rolf Klein
New Results on Visibility in Simple Polygons Algorithms and Data Structure Symposium, Banff, Canada,
LNCS 5664, Springer, 2009, pp. 327-338.