Perhaps you should try some spelling variations:
hoach thu » hoach thay, doanh thu, hoach su
nghiem tu » nghiep tu, nghiem te, nghiem xu
nghiem su » nghiem xu, nghiem ngu, nghiem dau
sach dat » sach dao, sach danh, sach bai
dat nghe » day nghe, da nghe, dang nghe
tu sach » thu sach, su sach, te sach
de hoc » te hoc, du hoc, dien hoc
d hoc » du hoc, ad hoc, y hoc

You may be able to get more results by adjusting your search query.

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