Jerabek, Jan, Roman Sotner, Tomas Dostal, and Kamil Vrba. 2015. “Simple Resistor-Less Generator Utilizing Z-Copy Controlled Gain Voltage Differencing Current Conveyor for PWM Generation”. Elektronika Ir Elektrotechnika 21 (5), 28-34. https://doi.org/10.5755/j01.eee.21.5.13322.