+}
+
+@book{ref222,
+ author = {S. Misra and I. Woungang and S. C. Misra},
+ title = {Guide to Wireless Sensor Networks},
+ publisher = {Springer-Verlag London Limited},
+ year = {2009},
+}
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+
+@article{ref223,
+ title={Wireless sensor networks: applications and challenges of ubiquitous sensing},
+ author={Puccinelli, Daniele and Haenggi, Martin},
+ journal={Circuits and Systems Magazine, IEEE},
+ volume={5},
+ number={3},
+ pages={19--31},
+ year={2005},
+ publisher={IEEE}
+}
+
+@inproceedings{ref224,
+ title={Probabilistic coverage in wireless sensor networks},
+ author={Ahmed, Nadeem and Kanhere, Salil S and Jha, Sanjay},
+ booktitle={Local Computer Networks, 2005. 30th Anniversary. The IEEE Conference on},
+ pages={8--pp},
+ year={2005},
+ organization={IEEE}
+}
+
+@inproceedings{ref225,
+ title={Incremental Model for Complete Area Coverage in Wireless Sensor Networks},
+ author={Sethi, Hemendra Kumar and Dash, Sasmita and Lenka, Manas Ranjan and Swain, Amulya Ratna},
+ booktitle={Computational Intelligence and Networks (CINE), 2015 International Conference on},
+ pages={92--97},
+ year={2015},
+ organization={IEEE}
+}
+
+@article{ref226,
+ title={Extending the Network Lifetime of Wireless Sensor Networks Using Residual Energy Extraction—Hybrid Scheduling Algorithm},
+ author={CHITRA, M},
+ journal={Int'l J. of Communications, Network and System Sciences},
+ volume={2010},
+ year={2010},
+ publisher={Scientific Research Publishing}
