Perhaps you should try some spelling variations:
thu doanh » thu oanh, tri doanh, thu hoach
nghiem su » nghiem xu, nghiem ngu, nghiem dau
va nghiem » van nghiem, va nghien, va nghiep
sach dat » sach dao, sach danh, sach xa
doanh va » doan va, doanh tai, doanh cua
sach bai » sach dao, cac bai, sach xa
sach day » sach dao, sach dau, sach hay
nghe d » nghe di, nghe _, nghe 新
su hoc » tu hoc, du hoc, so 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 day) or (((sach dat) OR (sach bai)))) nghe d hoc ) or ( thu doanh va nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach day) OR (((sach dat) OR (sach bai)))) nghe d hoc ) OR ( thu doanh va nghiem su hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((sach day) or (((sach dat) OR (sach bai)))) nghe d hoc ) or ( thu doanh va nghiem su hoc ))*".