@article{JIS_2009__12_1_a2,
     author = {Howard, Timothy and Ionascu, Eugen J. and Woolbright, David},
     title = {Introduction to the "prisoners and guards" game},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2009__12_1_a2/}
}