Perhaps you should try some spelling variations:
va nghiem » van nghiem, va nghien, va nghiep
thu doanh » thu oanh, tri doanh, thu hoach
nghiem su » nghiem xu, nghiem ngu, nghiem dau
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
doanh va » doan va, doanh tai, doanh cua
tu sach » thu sach, su sach, te sach
de hoc » te hoc, du hoc, dien hoc
su hoc » tu hoc, du hoc, so hoc
d hoc » du hoc, y hoc, _ 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 (ad hoc))) or (de hoc)) ) or ( thu doanh va nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dao nghe ((((d hoc) OR (ad hoc))) OR (de hoc)) ) OR ( thu doanh va nghiem su hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach dao nghe ((((d hoc) or (ad hoc))) or (de hoc)) ) or ( thu doanh va nghiem su hoc ))*.