Orman, Kamil, Abdullah Basci, and Adnan Derdiyok. 2016. “Speed and Direction Angle Control of Four Wheel Drive Skid-Steered Mobile Robot by Using Fractional Order PI Controller”. Elektronika Ir Elektrotechnika 22 (5):14 - 19. https://doi.org/10.5755/j01.eie.22.5.16337.