Perhaps you should try some spelling variations:
thi nghiem » thuc nghiem
hoach thi » hoach thu, hoach toi, hoach thay
nghiem so » nghiem son, nghiep so, nghiem su
tu sach » thu sach, su sach, tu cach
te sach » toc sach
nghe d » nghe di, nghe 新, nghe 1
so hoc » co hoc, mo hoc, so hoa

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