Perhaps you should try some spelling variations:
cong thanh » dong thanh, cong trinh, cong tan
tran chau » tranh chap, tran huu
theo dat » theo dau, theo luat, tren dat
dat sach » mat sach, dat khach, nam sach
vat dang » van dang, vat dung, vat dong
tran cau » toan cau, ran cau, tra cau
va dang » van dang, va nang, va lang

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: theo dat sach - canh tranh ((vat dang) OR (va dang)) cong thanh ((tran cau) OR (tran chau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo dat sach - canh tranh ((vat dang) or (va dang)) cong thanh ((tran cau) OR (tran chau))~".
• Adding a wildcard symbol may retrieve word variants: theo dat sach - canh tranh ((vat dang) or (va dang)) cong thanh ((tran cau) OR (tran chau))*.