Vavasis, Gerasimos, et al. “High School Students’ Difficulties and Their Causes Due to the Electromotive Force, in the Study of Direct Current Simple Electric Circuits”. International Journal of Recent Contributions from Engineering, Science & IT (iJES), vol. 10, no. 03, Nov. 2022, pp. pp. 4-18, doi:10.3991/ijes.v10i03.34375.