Perhaps you should try some spelling variations:
thi nghiem » thuc nghiem
thu nghiem » thuc nghiem
sach thu » sach thue, sach thieu, sach tham
sach thi » sach tai, sach thieu, sach tham
nghiem h » nghiem _, nghiem d, nghiem y
tu sach » thu sach, su sach, te sach
so sach » so sanh, bo sach, co sach
he ho » he kho, che ho, hue ho
h hoc » y hoc, _ hoc, o 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 thu nghiem ((he ho) or (hen ho)) ) or ( so sach thi nghiem h hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach thu nghiem ((he ho) OR (hen ho)) ) OR ( so sach thi nghiem h hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach thu nghiem ((he ho) or (hen ho)) ) or ( so sach thi nghiem h hoc ))*.