Here are some useful links for doing bibliographical research. Placed here, mostly so I can find them:

Union Catalog of Chinese Books in Japan (全國漢籍データベース)

http://kanji.zinbun.kyoto-u.ac.jp/kanseki

Union Catalog of Rare Books in Korea (한국고전적종합목록)

https://www.nl.go.kr/korcis/

Nom Foundation (for digitized Vietnamese materials)

http://lib.nomfoundation.org/collection/

Union Catalog of Chinese rare books at Chinese universities (學苑汲古 高校古文獻資源庫)

http://rbsc.calis.edu.cn:8086/aopac/jsp/indexXyjg.jsp