Perhaps you should try some spelling variations:
tai nghiem » trai nghiem, thi nghiem, trac nghiem
nghiem ad » nghiem d, nghiem ban, nghiem lam
sanh trac » anh trac, sinh trac, canh tac
sach tai » sach bai, sach tham, sach dao
trac che » cac che, tac cho, tai che
che duoc » che thuoc, che do, te duoc
duoc hoc » quoc hoi
su sach » so sach, vu sach
so sanh » do sanh

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 tai nghiem ad hoc ) or ( so sanh trac che duoc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tai nghiem ad hoc ) OR ( so sanh trac che duoc hoc ))*.