Perhaps you should try some spelling variations:
su nghiem » su nghiep, thu nghiem, so nghien
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
tu sach » thu sach, su sach, te sach
nghe d » nghe di, nghe _, nghe 新
su hoc » du hoc, so hoc, su ho
tu hoc » te hoc
d hoc » du hoc, ad hoc, de hoc

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 d hoc ) or ( thu hoach su nghiem ((su hoc) or (tu hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dao nghe d hoc ) OR ( thu hoach su nghiem ((su hoc) OR (tu hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach dao nghe d hoc ) or ( thu hoach su nghiem ((su hoc) or (tu hoc)) ))*.