Perhaps you should try some spelling variations:
hoach hoi » hoc hoi, sach hoi
nghiem su » nghiem xu, nghiem ngu, nghiem dau
sach dat » sach dao, sach danh, sach bai
dat nghe » day nghe, da nghe, dang nghe
hoach ha » hoach va, hoach xay, hoach su
tu sach » thu sach, su sach, te sach
de hoc » du hoc, dien 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 dat nghe ((te hoc) or (de hoc)) ) or ( thu ((hoach ha) or (hoach hoi)) nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dat nghe ((te hoc) OR (de hoc)) ) OR ( thu ((hoach ha) OR (hoach hoi)) nghiem su hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach dat nghe ((te hoc) or (de hoc)) ) or ( thu ((hoach ha) or (hoach hoi)) nghiem su hoc ))*.