Mihajlovic, Z., V. Milosavljevic, A. Joza, V. Rajs, M. Damnjanovic, and M. Zivanov. “Surface and Underground Water Level Monitoring Using Wireless Sensor Node With Energy Harvesting Support”. Elektronika Ir Elektrotechnika, vol. 22, no. 5, Oct. 2016, pp. 62 -68, doi:10.5755/j01.eie.22.5.16346.