Umar, L., Y. Hamzah, and R. N. Setiadi. “MULTI-CHANNEL FRY COUNTER DESIGN USING OPTOCOUPLER SENSOR”. Spektra: Jurnal Fisika Dan Aplikasinya, Vol. 4, no. 2, Aug. 2019, pp. 97 - 104, doi:10.21009/SPEKTRA.042.06.