Perhaps you should try some spelling variations:
va nghiem » van nghiem, va nghien, va nghiep
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
hoach va » hoach xay, hanh va, doanh va
tu sach » thu sach, su sach, te sach
su hoc » du hoc, su ho, su hoa
tu hoc » te hoc
so hoc » co hoc, mo hoc, so hoa

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 dao nghe _ hoc ) or ( thu hoach va nghiem ((((su hoc) OR (tu hoc))) or (so hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dao nghe _ hoc ) OR ( thu hoach va nghiem ((((su hoc) OR (tu hoc))) OR (so hoc)) ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach dao nghe _ hoc ) or ( thu hoach va nghiem ((((su hoc) OR (tu hoc))) or (so hoc)) ))*".