Perhaps you should try some spelling variations:
xay nghiem » xet nghiem, day nghiep, van nghiem
thu sach » thuat sach, thuoc sach, khau sach
day nghe » dang nghe, van nghe, nam nghe
tu sach » su sach, te sach, tu cach
nghe y » nghe sy, nghe _, nghe 新
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: (( ((tu sach) OR (thu sach)) day nghe y hoc ) or ( thu hoach xay nghiem ((su hoc) or (so hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((tu sach) OR (thu sach)) day nghe y hoc ) OR ( thu hoach xay nghiem ((su hoc) OR (so hoc)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((tu sach) OR (thu sach)) day nghe y hoc ) or ( thu hoach xay nghiem ((su hoc) or (so hoc)) ))".
• Adding a wildcard symbol may retrieve word variants: (( ((tu sach) OR (thu sach)) day nghe y hoc ) or ( thu hoach xay nghiem ((su hoc) or (so hoc)) ))*.