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
nghe de » nghe det, nghe di, nghe te
de hoc » te hoc, du hoc, dien hoc
su hoc » tu hoc, du hoc, su hoa
so hoc » co hoc, mo hoc, so hoa
su ho » su hoa, su pho, su co

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