Perhaps you should try some spelling variations:
huu them » huu thu, huu thuc, huu liem
vanh tai » van tai, hanh tai, anh tai
sach ky » sac ky, sach y, sach ty
huu tre » huu tri, cuu tre, huu tien
va vanh » va van, va danh, va hanh
qua cac » cua cac
nang mo » nang meo, nang ma, nang co
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa
mo hoc » mon hoc, co hoc

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: su ((sach ky) OR (cac ky)) nang mo hoc. hieu qua cac tuc va vanh tai ((huu tre) OR (huu them))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (cac ky)) nang mo hoc. hieu qua cac tuc va vanh tai ((huu tre) OR (huu them))~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (cac ky)) nang mo hoc. hieu qua cac tuc va vanh tai ((huu tre) OR (huu them))*.