volume={1},
pages={69--93},
year={1991}
+}
+
+@article{gentili2013,
+year={2013},
+journal={Optimization Letters},
+volume={7},
+number={1},
+title={α-Coverage to extend network lifetime on wireless sensor networks},
+publisher={Springer-Verlag},
+author={Gentili, Monica and Raiconi, Andrea},
+pages={157-172},
}
\ No newline at end of file