Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
su sach » so sach, vu sach
vu nang » vuc nang, vu dang, v nang
va nang » van nang, da nang, cam nang
cao hoi » cau hoi, co hoi, cao hoc
qua hau » qua hai, qua bau, qua dau
hau loc » huu loc, phau hoc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
loc va » hoc va, luc va
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((vu nang) OR (va nang)) cao hoi. hieu qua hau loc va hanh dai ((cua tre) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((vu nang) OR (va nang)) cao hoi. hieu qua hau loc va hanh dai ((cua tre) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((vu nang) OR (va nang)) cao hoi. hieu qua hau loc va hanh dai ((cua tre) or (cua tu))".
• Adding a wildcard symbol may retrieve word variants: su sach ((vu nang) OR (va nang)) cao hoi. hieu qua hau loc va hanh dai ((cua tre) or (cua tu))*.