Perhaps you should try some spelling variations:
thu nghiem » thuc nghiem, thi nghiem
nuoc sach » nguoi sach, hoc sach, cuoc cach
nghiem _u » nghiem su, nghiem xu, nghiem ngu
sach thu » sach thue, sach thieu, sach tham
sach dao » lanh dao
su sach » so sach, vu 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.

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach thu nghiem ((d hoc) OR (de hoc)) ) or ( nuoc sach dao ((nghiem _u) or (nghiem _)) hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach thu nghiem ((d hoc) OR (de hoc)) ) OR ( nuoc sach dao ((nghiem _u) OR (nghiem _)) hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach thu nghiem ((d hoc) OR (de hoc)) ) or ( nuoc sach dao ((nghiem _u) or (nghiem _)) hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( su sach thu nghiem ((d hoc) OR (de hoc)) ) or ( nuoc sach dao ((nghiem _u) or (nghiem _)) hoc ))*.