Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu xanh
chieu sang » chieu xanh, hieu lang, nhieu tang
dong cong » duong cong, dung cong, dang cong
van nang » van quang, van dong, van dung
nang duc » nang luc, nang doc, nang du
duc dong » duoc dong, duc dung, duc cong
cong tan » cong tac, cong san, cong thanh
tan van » tran van, tang van, luan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((chieu sach) or (chieu sang)) - van nang duc dong cong tan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((chieu sach) OR (chieu sang)) - van nang duc dong cong tan van ban*.