k. Abass, A., Mohammed J. Abdul-Razak, Haneen H. Mohammed, Suad M. Kadhim, and Mohammed A. Salih. “Optical Fiber Amplifiers: Optimization and Performance Evaluation”. Diyala Journal of Engineering Sciences, vol. 12, no. 1, Mar. 2019, pp. 66-72, doi:10.24237/djes.2019.12108.