Perhaps you should try some spelling variations:
sach trinh » sach tranh, hanh trinh, sach kinh
trinh nghe » trinh nghien, trinh he, trinh nha
khac trac » khac trai, khach trai, khai thac
trac nghe » trac nghiem, thai nghe, cac nghe
nghe duoc » nghiem duoc, nghe nuoi, che duoc
duoc hoc » quoc hoi
thai hoc » dai hoc, bai hoc, hoi hoc
su khac » vu khac, se khac, bui khac
su sach » so sach, vu sach
tai hoc » dai hoc, bai hoc, tri hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su khac trac nghe duoc hoc ) or ( su sach trinh nghe ((tai hoc) OR (thai hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su khac trac nghe duoc hoc ) OR ( su sach trinh nghe ((tai hoc) OR (thai hoc)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su khac trac nghe duoc hoc ) or ( su sach trinh nghe ((tai hoc) OR (thai hoc)) ))".
• Adding a wildcard symbol may retrieve word variants: (( su khac trac nghe duoc hoc ) or ( su sach trinh nghe ((tai hoc) OR (thai hoc)) ))*.