Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh nghe » trinh nghe, anh nghe, hanh nghe
bai nghiem » trai nghiem, thi nghiem, bai nghe
nghe duoc » nghiem duoc, nghe nuoi, che duoc
duoc hoc » quoc hoi
su sach » so sach, vu sach
hoc cac » hoc cao
d hoc » du hoc, de hoc, y 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 tranh nghe duoc hoc ) OR ( hoc cac bai nghiem ((d hoc) OR (ad hoc)) ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach tranh nghe duoc hoc ) or ( hoc cac bai nghiem ((d hoc) OR (ad hoc)) ))~".
• Adding a wildcard symbol may retrieve word variants: (( su sach tranh nghe duoc hoc ) or ( hoc cac bai nghiem ((d hoc) OR (ad hoc)) ))*.