Perhaps you should try some spelling variations:
xay nghiem » xet nghiem, day nghiep, van nghiem
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
tu sach » thu sach, su sach, te sach
nghe ad » nghe adn, nghe cad, nghe ar
su pho » sau pho, su phong
so hoc » co hoc, mo hoc, so hoa
su ho » su hoa, su hoc, su co

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