Perhaps you should try some spelling variations:
nghiem dan » nghiem ban, nghiem van, nghiem dau
ha nghiem » khao nghiem, thi nghiem, thu nghiem
sach dat » sach dao, sach danh, sach bai
hoach ha » hoach va, hoach xay, hoach hoi
sach da » sach dao, sach dau, sach xa
dan hoc » van hoc, dan toc, dai hoc
tu hoc » te hoc
de hoc » te hoc, du hoc, dien 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 da) OR (sach dat)) nghe ((tu hoc) or (de hoc)) ) or ( thu hoach ha nghiem dan hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach da) OR (sach dat)) nghe ((tu hoc) OR (de hoc)) ) OR ( thu hoach ha nghiem dan hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((sach da) OR (sach dat)) nghe ((tu hoc) or (de hoc)) ) or ( thu hoach ha nghiem dan hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach da) OR (sach dat)) nghe ((tu hoc) or (de hoc)) ) or ( thu hoach ha nghiem dan hoc ))*.