A. Q. Guillermo, M. A. Bajet, Jr., and D. F. Tolentino, “Effectiveness of the Two-in-One Device; Ignition Coil and Spark Plug Testing Instrument”, jpair, vol. 20, no. 1, pp. 83–103, Mar. 2015, doi: 10.7719/jpair.v20i1.320.