Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
sang tao » hang tai
cua tre » cua te, cuu tre, cua triet
dinh vi » dinh ve, dinh tri, dinh thi
nam duc » nam duoc, pham duc, nam thuc
hieu va » lieu va, hieu qua
sang ma » tang ma, nang ma, mang may
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay
te sac » te sach, te cac, te san

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((sang ma) OR (sang tao)) hoi. hieu va nam duc va ((dinh vi) or (dinh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((sang ma) OR (sang tao)) hoi. hieu va nam duc va ((dinh vi) OR (dinh viet)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((sang ma) OR (sang tao)) hoi. hieu va nam duc va ((dinh vi) or (dinh viet)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((sang ma) OR (sang tao)) hoi. hieu va nam duc va ((dinh vi) or (dinh viet)) cua tre*.