Seifouri, M., M. M. Karkhanehchi, and S. Rohani. 2012. “Design of Multi-Layer Optical Fibers With Ring Refractive Index to Reduce Dispersion and Increase Bandwidth in Broadband Optical Networks”. Engineering, Technology & Applied Science Research 2 (3). Greece:216-20. https://doi.org/10.48084/etasr.166.