Perhaps you should try some spelling variations:
tham nghiem » trac nghiem, thuc nghiem, thi nghiem
trai nghiem » trac nghiem, thi nghiem
khach trai » khac trai, khanh tra, kham trai
sach tham » sach nha
nghiem de » nghiem d, nghiem te, nghiem dau
nghiem ve » nghiem va, nghiem vi, nghiem te
te khach » he khach, tri khach, tan khach
tu sach » thu sach, su sach, te sach
de hoc » te hoc, du hoc, dien hoc
ve hoc » te hoc, va hoc, vi 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 tham nghiem de hoc ) or ( te khach trai nghiem ve hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tham nghiem de hoc ) OR ( te khach trai nghiem ve hoc ))*.