Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
vai cua » dai cua, hai cua, lai cua
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
va dao » ca dao

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 ty nang ma hoi. ((hieu ve) or (hieu qua)) cac thuc ((va dau) or (va dao)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ma hoi. ((hieu ve) OR (hieu qua)) cac thuc ((va dau) OR (va dao)) vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ma hoi. ((hieu ve) or (hieu qua)) cac thuc ((va dau) or (va dao)) vai cua tre*.