Perhaps you should try some spelling variations:
thu doanh » thu oanh, tri doanh, thu hoach
va nghiep » va nghien, lam nghiep, cac nghiep
doanh va » doan va, doanh tai, doanh cua
te sach » toc sach
sach da » sach dao, sach dat, sach dau
da nghe » day nghe, va nghe, dang nghe
de hoc » te hoc, du hoc, dien hoc
su hoc » du hoc, so hoc, su ho
tu hoc » te hoc
d hoc » du hoc, ad hoc, y hoc

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