Perhaps you should try some spelling variations:
xay nghiem » xet nghiem, day nghiep, van nghiem
nghiem tu » nghiep tu, nghiem su, nghiem te
dao nghe » day nghe, da nghe, nao nghe
dat nghe » day nghe, da nghe, dang nghe
tu sach » thu sach, su sach, te sach
du hoc » duoc hoc
tu hoc » te hoc
d hoc » ad hoc, de hoc, y 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 ((dao nghe) OR (dat nghe)) ((d hoc) or (du hoc)) ) or ( thu hoach xay nghiem tu hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ((dao nghe) OR (dat nghe)) ((d hoc) OR (du hoc)) ) OR ( thu hoach xay nghiem tu hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach ((dao nghe) OR (dat nghe)) ((d hoc) or (du hoc)) ) or ( thu hoach xay nghiem tu hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach ((dao nghe) OR (dat nghe)) ((d hoc) or (du hoc)) ) or ( thu hoach xay nghiem tu hoc ))*.