Balaševičius, L., V. S. Januševičius, and S. Zakaraitė. “State Controller Design in Programmable Logic Controllers”. Elektronika Ir Elektrotechnika, vol. 81, no. 1, Jan. 2008, pp. 19-22, https://eejournal.ktu.lt/index.php/elt/article/view/11026.