Rattha, P., V. Chamnanphrai, A. Charoenmee, and J. Namsom. “Guidelines for the Development of Power Loss Reduction Circuits of Class A Audio Amplifiers Using Appropriated Voltage Adjustment Technique With Small Input Signal: Doi: 10.14456/Mijet.2020.7”. Engineering Access, vol. 6, no. 1, Jan. 2020, pp. 30-35, https://ph02.tci-thaijo.org/index.php/mijet/article/view/10.14456.mijet.2020.7.