Perhaps you should try some spelling variations:
ha nghiem » khao nghiem, thi nghiem, thu nghiem
hoach ha » hoach va, hoach xay, hoach hoi
te sach » toc sach
sach va » sach xa, sach ha, sach dao
va nghe » van nghe, ve nghe, va nghi
su hoc » tu hoc, du hoc, su ho
so hoc » co hoc, mo hoc, so hoa

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 va nghe ((y hoc) or (te hoc)) ) or ( thu hoach ha nghiem ((su hoc) OR (so hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach va nghe ((y hoc) OR (te hoc)) ) OR ( thu hoach ha nghiem ((su hoc) OR (so hoc)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach va nghe ((y hoc) or (te hoc)) ) or ( thu hoach ha nghiem ((su hoc) OR (so hoc)) ))".
• Adding a wildcard symbol may retrieve word variants: (( te sach va nghe ((y hoc) or (te hoc)) ) or ( thu hoach ha nghiem ((su hoc) OR (so hoc)) ))*.