Hung, William, and Harvard-Yenching Institute. Yinde bianzuan chu. Harvard-Yenching Institute Sinological Index Series. Ha-fo Yanjing xueshe yinde tekan. Taiwan authorized reprint ed. Taibei: Chengwen Publishing Company: Distributed by Chinese Materials and Research Aids Service Center, 1966.
This series is recognized as the most comprehensive effort to index Chinese classical works. Although dated, it is recommended as the first step in one’s index search.
Academia Sinica. Academia Sinica Computing Centre. 漢籍電子文獻.
This site allows the researcher to perform a keyword search in all of the 25 Dynastic Histories and the 13 Classics (Shisan Jing), among others. Institutional subscription required for use.