Perhaps you should try some spelling variations:
hoach thay » hoach toan, hoach xay, hoach ha
hoach thi » hoach thu, hoach toi, hoang thi
nghiem so » nghiem son, nghiep so, nghiem su
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
tu sach » thu sach, su sach, te sach
du hoc » tu hoc, duoc hoc
so hoc » co hoc, mo hoc, so hoa
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 ((d hoc) or (du hoc)) ) or ( thu ((hoach thi) OR (hoach thay)) nghiem so hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dao nghe ((d hoc) OR (du hoc)) ) OR ( thu ((hoach thi) OR (hoach thay)) nghiem so hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach dao nghe ((d hoc) or (du hoc)) ) or ( thu ((hoach thi) OR (hoach thay)) nghiem so hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach dao nghe ((d hoc) or (du hoc)) ) or ( thu ((hoach thi) OR (hoach thay)) nghiem so hoc ))*.