Gu, Y., and S. He. “Case Studies on Upgradable Engineering Design As a Powerful Tool for Air Force Industry”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 45, no. 1, Mar. 2019, pp. 43-52, https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/9846.