Perhaps you should try some spelling variations:
thieu nien » thien nhien
nien cac » vien cac, dien cac, bien cac
nang tai » hang tai, tang tai, sang tai
cac truc » cau truc, cac tru, cac trung
su viet » so viet
va nang » van nang, da nang, cam nang
truc va » thuc va, thuc vat, trung va
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
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: tu ((sach ky) or (sac ky)) nang ma hoi. thieu nien cac truc va nang tai ((su viet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang ma hoi. thieu nien cac truc va nang tai ((su viet) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang ma hoi. thieu nien cac truc va nang tai ((su viet) or (va thiet))*.