1. Allum, J., & Talbot, C. (2018). Physics for the IB diploma, hodder education (p. 509).
2. Calvin, S. (2004). Following in Einstein’s footsteps: Teaching the photoelectric effect. The Physics Teacher, 42(6), 340–341.
3. Cutnell, J., & Johnson, K. W. (2007). Physics (Vol. 2, 7th ed., p. 919). New Wiley & Sons, Inc..
4. Earle, G. D., Copp, B. L., Klenzing, J. H., & Bishop, R. L. (2003). A novel empirical study of the photoelectric effect in thin gold films. American Journal of Physics, 71(8), 766–769.
5. Giancoli, D. C. (2005). Physics: Principles with applications (6th ed., p. 760). Prentice-Hall.