Perhaps you should try some spelling variations:
hieu sach » chieu sach, hieu cach, hieu cac
dien sach » dien anh
chua dang » cua dang, chua dong, chua nang
dang cong » dung cong
cong canh » cong danh, cong thanh, cong khanh
anh dang » anh dong, anh dung, anh bang
canh van » anh van, can van, cach van

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) or (dien sach)) - ((canh tranh) or (anh dang)) chua dang cong canh van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sach) OR (dien sach)) - ((canh tranh) OR (anh dang)) chua dang cong canh van ban.
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) or (dien sach)) - ((canh tranh) or (anh dang)) chua dang cong canh van ban*.