Sokmen, O. G., H. Ercan, S. A. Tekin, and M. Alci. “A Novel Low Voltage Low Power OTA Based on Level Shifter Current Mirror”. Elektronika Ir Elektrotechnika, vol. 21, no. 2, Apr. 2015, pp. 39-43, doi:10.5755/j01.eee.21.2.11511.