Perhaps you should try some spelling variations:
thieu nghe » thieu nhi, lieu nghe, nhiem nghe
nghiem xu » nghiem su, nghiem xuan, nghiem ngu
nghi xuan » nghiem xuan, ngo xuan, thi xuan
nghe duoc » nghiem duoc, nghe nuoi, che duoc
duoc hoc » quoc hoi
su canh » suc canh, su can, su anh
vu sach » vu bach, su sach, 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 canh tranh ((nghiem xu) or (nghi xuan)) hoc ) or ( vu sach thieu nghe duoc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su canh tranh ((nghiem xu) OR (nghi xuan)) hoc ) OR ( vu sach thieu nghe duoc hoc )).
• Adding a wildcard symbol may retrieve word variants: (( su canh tranh ((nghiem xu) or (nghi xuan)) hoc ) or ( vu sach thieu nghe duoc hoc ))*.