Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thuc day » thuc dan, thuc vat
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
hieu vi » hieu voi, hieu va, hieu ve
thuc va » thuc vat, thuc dan
su tien » su kien, su hien, tu tieng
san su » dan su, van su, ban su

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky nang cao hoi. hieu vi pham ((thuc va) or (thuc day)) thanh san su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang cao hoi. hieu vi pham ((thuc va) OR (thuc day)) thanh san su tien.
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang cao hoi. hieu vi pham ((thuc va) or (thuc day)) thanh san su tien*.