Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, dien sach
trinh che » trinh he, trinh cho, trinh chu
doc hieu » toc thieu, hoc thieu, hoc hien
che nang » cho nang, chuc nang, chua nang
cong van » cong vang, cong san, cong tan
song van » hoang van, trong van, duong van
tuan cau » toan cau, quan cau, tuan cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu sach - cong trinh che nang ((cong van) or (song van)) tuan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sach - cong trinh che nang ((cong van) OR (song van)) tuan cau.
• Adding a wildcard symbol may retrieve word variants: doc hieu sach - cong trinh che nang ((cong van) or (song van)) tuan cau*.