Wai, M. P. P., P. Suwanjan, W. Jaikla, and A. Chaichana. “Electronically and Orthogonally Tunable SITO Voltage-Mode Multifunction Biquad Filter Using LT1228s”. Elektronika Ir Elektrotechnika, vol. 1, no. 1, Sept. 2021, doi:10.5755/j02.eie.28949.