Xú Yōng 徐鏞 (Qīng physician, zì and lifedates unrecovered), mid-Qīng author of the Yīxué jǔyào 醫學舉要 (KR3er006). The work cites both 葉桂 Yè Tiānshì’s Línzhèng zhǐnán yīàn (1764) and 徐大椿 Xú Dàchūn’s Yīxué yuánliú lùn (1757), bracketing Xú Yōng’s medical practice and the composition of his work to the second quarter of the nineteenth century. CBDB returns multiple homonymous 徐鏞 entries; CBDB 61782 (Qīng, c_index_year 1779) is the most plausible candidate, though the work’s substantive evidence (developed mid-late Qīng Shānghán-revisionist programme drawing on Chéng Jiāoqiàn and Kē Yùnbó) suggests a later flourishing — probably the 1830s–1860s. Without further documentary evidence Xú Yōng remains undatable with precision.