Perhaps you should try some spelling variations:
van nghiem » van nghe, van nghia, quang nghiem
hoach van » hoach va, hoach san, hoach toan
dao nghe » da nghe, dat nghe, nao nghe
day nghe » dang nghe, van nghe, nam nghe
tu sach » thu sach, su sach, te sach
so hoc » co hoc, mo hoc, so hoa
su ho » su hoa, su hoc, su pho

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