Perhaps you should try some spelling variations:
thanh duc » thach duc, than duc, thinh duc
qua thanh » quan thanh, cua thanh, qua than
hanh lai » hanh lam, hanh tai, thanh lap
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, co hoi, cao hoc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ky) or (sac ky)) nang cao hoi. hieu qua thanh duc va hanh lai ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sac ky)) nang cao hoi. hieu qua thanh duc va hanh lai ((cua tre) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sac ky)) nang cao hoi. hieu qua thanh duc va hanh lai ((cua tre) OR (cuu tre))*".