+}
+
+@article{rossi2012exact,
+ title={An exact approach for maximizing the lifetime of sensor networks with adjustable sensing ranges},
+ author={Rossi, Andr{\'e} and Singh, Alok and Sevaux, Marc},
+ journal={Computers \& Operations Research},
+ volume={39},
+ number={12},
+ pages={3166--3176},
+ year={2012},
+ publisher={Elsevier}
+}
+
+ @inproceedings{chenait2013distributed,
+ title={Distributed and stable energy-efficient scheduling algorithm for coverage in wireless sensor networks},
+ author={Chenait, Manel and Zebbane, Bahia and Belbezza, Hamza and Balli, Hakim and Badache, Nadjib},
+ booktitle={Wireless Communications and Mobile Computing Conference (IWCMC), 2013 9th International},
+ pages={418--423},
+ year={2013},
+ organization={IEEE}
+}
+
+@inproceedings{yangnovel,
+ title={A Novel Distributed Algorithm for Complete Targets Coverage in Energy Harvesting Wireless Sensor Networks },
+ author={Yang, Changlin and Chin, Kwan-Wu},
+ booktitle={IEEE ICC 2014- Ad-hoc and Sensor Networking Symposium},
+ pages={361--366},
+ year={2014},
+ organization={IEEE}
+}
+
+@inproceedings{Kumar:2005,
+ author = {Kumar, Santosh and Lai, Ten H. and Arora, Anish},
+ title = {Barrier Coverage with Wireless Sensors},
+ booktitle = {Proceedings of the 11th Annual International Conference on Mobile Computing and Networking},
+ series = {MobiCom '05},
+ year = {2005},
+ isbn = {1-59593-020-5},
+ location = {Cologne, Germany},
+ pages = {284--298},
+ numpages = {15},
+ url = {http://doi.acm.org/10.1145/1080829.1080859},
+ doi = {10.1145/1080829.1080859},
+ acmid = {1080859},
+ publisher = {ACM},
+ address = {New York, NY, USA},
+ keywords = {barrier coverage, coverage, critical conditions, localized algorithms, network topology, random geometric graphs, wireless sensor networks},
+}
+
+@article{Deng2012,
+ title={Transforming Area Coverage to Target Coverage to Maintain Coverage and Connectivity for Wireless Sensor Networks},
+ author={Xiu Deng and Jiguo Yu, Dongxiao Yu and Congcong Chen},
+ journal={International Journal of Distributed Sensor Networks},
+ volume={2012},
+ year={2012},
+ ee = {http://dx.doi.org/10.1155/2012/254318}
+}
+
+ @inproceedings{jaggi2006,
+ title={Energy-efficient Connected Covereage in Wireless Sensor Networks},
+ author={N. Jaggi and A.A. Abouzeid},
+ booktitle={Proceeding of 4th Asian International Mobile Computing Conference AMOC2006},
+ year={2006}
+}
+
+@INPROCEEDINGS{5714480,
+author={Xiaofei Xing and Jie Li and Guojun Wang},
+booktitle={Mobile Ad-hoc and Sensor Networks (MSN), 2010 Sixth International Conference on},
+title={Integer Programming Scheme for Target Coverage in Heterogeneous Wireless Sensor Networks},
+year={2010},
+month={Dec},
+pages={79-84},
+keywords={energy conservation;integer programming;wireless sensor networks;ETCA;clustered configurations;clusterheads;energy first algorithm;energy-efficient target coverage algorithm;heterogeneous wireless sensor networks;integer programming;network lifetime;polytype target coverage;sensor node;Algorithm design and analysis;Clustering algorithms;Energy consumption;Logic gates;Sensors;Simulation;Wireless sensor networks;Heterogeneous wireless sensor networks;network lifetime;optimization;target coverage},
+doi={10.1109/MSN.2010.18},}
+
+@article{Yang2014,
+ title={A Maximum Lifetime Coverage Algorithm Based on Linear Programming},
+ author={Mengmeng Yang and Jie Liu},
+ journal={Journal of Information Hiding an dMultimedia Signal Processing, Ubiquitous International},
+ volume={5},
+ number={2},
+ pages={296-301},
+ year={2014}
+}
+
+
+@article{ref17,
+ title={A survey on sensor networks},
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+ number={8},
+ pages={102--114},
+ year={2002},
+ publisher={IEEE}
+}
+
+@book{ref19,
+ title={Wireless sensor networks},
+ author={Akyildiz, Ian F and Vuran, Mehmet Can},
+ volume={4},
+ year={2010},
+ publisher={John Wiley \& Sons}
+}
+
+@article{ref22,
+ title={Energy efficiency in wireless sensor networks: A top-down survey},
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+ journal={Computer Networks},
+ volume={67},
+ pages={104--122},
+ year={2014},
+ publisher={Elsevier}
