Perhaps you should try some spelling variations:
ha nghiem » khao nghiem, thi nghiem, thu nghiem
thu sach » thuat sach, thuoc sach, khau sach
bai nghe » thai nghe, van nghe, cap nghe
nam nghe » nang nghe, van nghe
hoach ha » hoach va, hoach xay, hoach hoi
tu sach » su sach, te sach, tu cach
d hoc » du hoc, ad hoc, de 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 (thu sach)) ((bai nghe) or (nam nghe)) d hoc ) or ( thu hoach ha nghiem ngu hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((tu sach) OR (thu sach)) ((bai nghe) OR (nam nghe)) d hoc ) OR ( thu hoach ha nghiem ngu hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((tu sach) OR (thu sach)) ((bai nghe) or (nam nghe)) d hoc ) or ( thu hoach ha nghiem ngu hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( ((tu sach) OR (thu sach)) ((bai nghe) or (nam nghe)) d hoc ) or ( thu hoach ha nghiem ngu hoc ))*.