Perhaps you should try some spelling variations:
thue nghien » thuyet nghien, thuc nghiem, thu nghiem
thi nghiem » thuc nghiem
nghiem du » nghiem dau, nghiem d, nghiem de
sach thue » sach thu, sach thieu, sach tham
sach thi » sach thu, sach tai, sach thieu
su sach » so sach
vu sach » vu bach, vu khach
cuu hoi » cau hoi, cua hoi, cuu hoc
du hoc » tu hoc, duoc hoc

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach thi nghiem du hoc ) OR ( vu sach thue nghien cuu hoi ))~.
• Adding a wildcard symbol may retrieve word variants: (( su sach thi nghiem du hoc ) or ( vu sach thue nghien cuu hoi ))*.