Mirela Damian-Iordache Sriram V. Pemmaraju Constant-Factor Approximation Algorithms for Domination Problems on Circle Graphs. 70-82 http://dx.doi.org/10.1007/3-540-46632-0_8 1999 conf/isaac/1999 ISAAC db/conf/isaac/isaac99.html#Damian-IordacheP99a