Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, dien sach
hanh dang » hanh dong, anh dang, hanh dung
tdung dat » trung dai, vung dat, dong dat
doc hieu » toc thieu, hoc thieu, hoc hien
dang dan » dang dang, dang van, dung dan
dan dung » van dung, tin dung, ap dung
dung dat » dung va, dung tai

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 - hanh dang dan dung ((tdung dat) or (dung dat)) phan tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sach - hanh dang dan dung ((tdung dat) OR (dung dat)) phan tu.
• Adding a wildcard symbol may retrieve word variants: doc hieu sach - hanh dang dan dung ((tdung dat) or (dung dat)) phan tu*.