The Xu xuanguailu 續玄怪錄 "Continued tales of mysteries and monsters" is a collection of stories compiled by the Tang period 唐 (618-907) scholar Li Fuyan 李復言. Of his life not much is known. He seems to have lived during the Dahe 大和 and Kaicheng 開成 reigns (827-840), came from Longxi 隴西 (modern Lintao 臨洮, Gansu) and around 830 traveled to the region of modern Sichuan where he met the scholar Shen Tianxiang 沈田相 and decided to write a kind of supplement to Niu Sengru's 牛僧孺 Xuangailu 玄怪錄. It is also assumed that Li Fuyan is identical to Li Liang 李諒 (775-833) who was military commissioner (jiedushi 節度使) of Lingnan 嶺南 and was befriended to Bai Juyi 白居易 and Yuan Zhen 元稹, yet this interpretation is rather unprobable because of many discrepancies between Li Liang's collection Hang Yue ji he shi ji 杭越寄和詩集 and the Xu xuanguailu.
The Xu xuanguailu includes many stories that are very famous, like the elegantly written story Xin Gongping shang xian 辛公平上仙, the transformation of a man into a fish in Xue Wei 薛偉, the metamorphosis of a man into a tiger in Zhang Feng 張逢, the story of the marriage of Wei Gu 韋固 in Dinghundian 定婚店, or general Li Jing's 李靖 acting as the god of rain.
The imperial bibliography in the official dynastic history Xintangshu 新唐書 lists the Xu xuanguailu with a length of 5 juan "scrolls" (or ten semi-scrolls). The bibliography Junzhai duzhu zhi 郡齋讀書志 says that it was divided into two chapters, namely Xianshu 仙術 "The art of immortality", and Ganying 感應 "Retribution in a later life". The received version has a length of 4 juan and includes 23 stories. This version is a later compilation and not identical to the original, as can be seen in quotations in the encyclopedia Taiping guangji 太平廣記 that are not included in the modern version. The Xu xuanguailu was often printed together with the Xuanguailu, so that it is often not clear whether a story was included in the former or the latter.
The Xu xuanguailu is included in the collectanea Shuofu 說郛, Wuchao xiaoshuo 五朝小說, Tangren shuohui 唐人說薈, Tang-Song congshu 唐代叢書, Longwei mishu 龍威秘書, Xu guyi congshu 續古逸叢書, Sibu congkan xubian 四部叢刊續編, Linlang mishi congshu 琳瑯秘室叢書 and Sui'an congshu 隨庵叢書. A modern version was published by the Zhonghua shuju press 中華書局 in 1982.
Cheng Yizhong 程毅中 (1986). "Xuanguailu 玄怪錄", in: Zhongguo da baike quanshu 中國大百科全書, Zhongguo wenxue 中國文學, vol. 2, p. 1123. Beijing/Shanghai: Zhongguo da baike quanshu chubanshe.
Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 2141. Changchun: Jilin daxue chubanshe.