Perhaps you should try some spelling variations:
ha nghiem » khao nghiem, thi nghiem, thu nghiem
nghiem su » nghiem xu, nghiem ngu, nghiem dau
sach day » sach dao, sach dat, sach hay
sach dau » sach dao, sach dat, sach mau
hoach ha » hoach va, hoach xay, hoach hoi
nghe ad » nghe adn, nghe cad, nghe ar
su hoc » tu hoc, du hoc, so 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 dau)) nghe ad hoc ) or ( thu hoach ha nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach day) OR (sach dau)) nghe ad hoc ) OR ( thu hoach ha nghiem su hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach day) or (sach dau)) nghe ad hoc ) or ( thu hoach ha nghiem su hoc ))*.