Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, theo sach
thanh tung » thanh cong
hieu cach » hieu cac, chieu sach, hieu ca
hang cong » dang cong, hang nong, bang cong
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap
tung va » trung va, tuong va, dung va
va hang » van hang, va nang, va lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sach) or (hieu cach)) - thanh tung va hang cong dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (hieu cach)) - thanh tung va hang cong dan than cau.
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (hieu cach)) - thanh tung va hang cong dan than cau*.