Clayton W. Commander Michelle A. Ragle Yinyu Ye Semidefinite Programming and the Sensor Network Localization Problem, SNLP. 3384-3390 2009 Encyclopedia of Optimization http://dx.doi.org/10.1007/978-0-387-74759-0_581 reference/opt/2009 db/reference/opt/opt2009.html#CommanderRY09