Perhaps you should try some spelling variations:
cac tac » cac toc, cac bac, cac dac
cac cau » cac mau, bac cau, cac cam
sach ky » sac ky, sach y, sach ty
te sach » toc sach
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
ve cac » va cac, vien cac
ca dan » cac dan, ca dao
ca cau » cua cau, can cau, ca cac
va dau » va dao

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 ve cac tac ((va dau) or (ca dan)) ((ca cau) OR (cac cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang cao hoi. hieu ve cac tac ((va dau) OR (ca dan)) ((ca cau) OR (cac cau)) tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang cao hoi. hieu ve cac tac ((va dau) or (ca dan)) ((ca cau) OR (cac cau)) tren*".