Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
may minh » may tinh, mai minh, van minh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va
hoi cua » hoi chuc
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang cao hoi. ((hieu va) or (hieu qua)) nam thuc ((may minh) or (gia thanh)) hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang cao hoi. ((hieu va) OR (hieu qua)) nam thuc ((may minh) OR (gia thanh)) hoi cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ky nang cao hoi. ((hieu va) or (hieu qua)) nam thuc ((may minh) or (gia thanh)) hoi cua tre*.