Perhaps you should try some spelling variations:
sach tranh » canh tranh
nghiem xu » nghiem su, nghiem xuan, nghiem ngu
nghe quoc » nghe duoc, nghiem quoc, nghiep quoc
ngo xuan » ngo van
sach thi » sach thu, sach tai, sach thieu
thi nghe » thai nghe, thi nghiem, thi ngoc
su sach » so sach
vu sach » vu bach, vu khach

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 tranh ((nghiem xu) or (ngo xuan)) hoc ) or ( vu sach thi nghe quoc hoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tranh ((nghiem xu) OR (ngo xuan)) hoc ) OR ( vu sach thi nghe quoc hoi )).
• Adding a wildcard symbol may retrieve word variants: (( su sach tranh ((nghiem xu) or (ngo xuan)) hoc ) or ( vu sach thi nghe quoc hoi ))*.