Hao Sun, Jitao Sun, Li Zeng, Yifan Liang, Lingjun Tu, Huaiqian Yi, Qinming Li, Xiaofan Wang, Yong Yu, Jiayue Yang, Zhigang He, Yuhuan Tian, Likai Wang, Zequn Wang, Guorong Wu, Weiqing Zhang, Xueming Yang. "Demonstration of direct-amplification enabled harmonic generation in an ultraviolet free-electron laser." Applied Physics Letters, 2025. doi:10.1063/5.0287044