Perhaps you should try some spelling variations:
khao nghiem » khao nghiep
hoach khao » hoach ha, hoach giao, hoach thay
dao nghe » day nghe, da nghe, dat nghe
tu sach » thu sach, su sach, te sach
so sach » so sanh, bo sach, co sach
nghe de » nghe det, nghe di, nghe te
de hoc » te hoc, du hoc, dien hoc
xu hoc » tu hoc, du hoc, xa hoc
su hoc » tu hoc, du hoc, so 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) or (so sach)) dao nghe de hoc ) or ( thu hoach khao nghiem ((xu hoc) OR (su hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((tu sach) OR (so sach)) dao nghe de hoc ) OR ( thu hoach khao nghiem ((xu hoc) OR (su hoc)) ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((tu sach) or (so sach)) dao nghe de hoc ) or ( thu hoach khao nghiem ((xu hoc) OR (su hoc)) ))*".