Perhaps you should try some spelling variations:
nghiem su » nghiem xu, nghiem ngu, nghiem dau
ha nghiem » khao nghiem, thi nghiem, thu nghiem
hoach ha » hoach va, hoach xay, hoach hoi
sach bai » sach dao, cac bai
nghe vi » nghe va, nghe noi
sach xa » sach dao, sach nha
nghe di » nghe dien, nghe dan, nghe noi
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 bai) or (sach xa)) ((nghe di) OR (nghe vi)) hoc ) or ( thu hoach ha nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach bai) OR (sach xa)) ((nghe di) OR (nghe vi)) hoc ) OR ( thu hoach ha nghiem su hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((sach bai) or (sach xa)) ((nghe di) OR (nghe vi)) hoc ) or ( thu hoach ha nghiem su hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach bai) or (sach xa)) ((nghe di) OR (nghe vi)) hoc ) or ( thu hoach ha nghiem su hoc ))*.