Perhaps you should try some spelling variations:
thieu sach » chieu sach, thien hach, hieu cach
thanh tung » thanh cong
trong dong » trong cong, trong dang, trong dung
trong nong » trong cong
hoc thieu » toc thieu, hoc hien
vat dung » van dung, va dung, viet dung
toan cau » toan cao, toan ban, toan tap

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thieu sach - ((thanh trung) OR (thanh tung)) vat dung ((trong dong) OR (trong nong)) toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thieu sach - ((thanh trung) or (thanh tung)) vat dung ((trong dong) OR (trong nong)) toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc thieu sach - ((thanh trung) or (thanh tung)) vat dung ((trong dong) OR (trong nong)) toan cau*.