1. A combinatorial theorem in plane geometry;Chvatal;J. Combinatorial Theory. Series B,1975
2. A short proof of Chvatal's watchman theorem;Fisk;J. Combinatorial Theory. Series B,1978
3. Traditional galleries require fewer watch-men;Kahn;SIAM J. Alg.Discrete Meth.,1983
4. Art gallery theorems and algorithms;O’Rourke,1987
5. The art gallery theorem for polygons with holes;Hoffmann;Proc. 32nd Symp. Found. Comp. Sc. (1991),1991