Perhaps you should try some spelling variations:
xay nghiem » xet nghiem, day nghiep, van nghiem
sach dang » sach dung, sach danh, sach nang
dang nghe » lang nghe, nang nghe, cong nghe
nghiem su » nghiem xu, nghiem ngu, nghiem dau
tu sach » thu sach, su sach, te sach
du hoc » tu hoc, duoc hoc
de hoc » te hoc, dien hoc
su hoc » tu hoc, so hoc, su ho
d hoc » ad hoc, y hoc, _ 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 dang nghe ((((d hoc) OR (du hoc))) or (de hoc)) ) or ( thu hoach xay nghiem su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dang nghe ((((d hoc) OR (du hoc))) OR (de hoc)) ) OR ( thu hoach xay nghiem su hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach dang nghe ((((d hoc) OR (du hoc))) or (de hoc)) ) or ( thu hoach xay nghiem su hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach dang nghe ((((d hoc) OR (du hoc))) or (de hoc)) ) or ( thu hoach xay nghiem su hoc ))*.