+
+@article{ref239,
+author = {Hung, Ka-Shun and Lui, King-Shan},
+title = {Perimeter Coverage Scheduling in Wireless Sensor Networks Using Sensors with a Single Continuous Cover Range},
+journal = {EURASIP Journal on Wireless Communications and Networking },
+volume = {2010},
+year = {2010}
+}
+
+@article{ref240,
+ title={Solving the cell suppression problem on tabular data with linear constraints},
+ author={Fischetti, Matteo and Salazar, Juan Jos{\'e}},
+ journal={Management Science},
+ volume={47},
+ number={7},
+ pages={1008--1027},
+ year={2001},
+ publisher={INFORMS}
+}
\ No newline at end of file
