Perhaps you should try some spelling variations:
dao nghiem » khao nghiem, van nghiem, vao nghien
thuoc sach » hoc sach, nuoc sach, thuat sach
sach dao » lanh dao
nghiem d » nghiem de, nghiem do, nghiem _
tai nghe » bai nghe, tam nghe, tao nghe
vu sach » vu bach, su sach, vu khach
d hoc » du hoc, ad hoc, de 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: (( vu sach dao nghiem d hoc ) OR ( thuoc sach ((tai nghe) OR (thai nghe)) quoc hoi ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu sach dao nghiem d hoc ) or ( thuoc sach ((tai nghe) OR (thai nghe)) quoc hoi ))~".
• Adding a wildcard symbol may retrieve word variants: (( vu sach dao nghiem d hoc ) or ( thuoc sach ((tai nghe) OR (thai nghe)) quoc hoi ))*.