Kher-Elden, M. A., Z. M. Abd El-Fattah, O. Yassin, and M. M. El-Okr. 2017. “Tuning the Indirect Band Gap of Square Metallic Superlattices”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 35 (2):113-22. https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/7868.