Perhaps you should try some spelling variations:
sach tranh » canh tranh
thuoc sach » hoc sach, nuoc sach, thuat sach
nghiem dau » nghiep dau, nghiem va, nghiem ban
nghiem du » nghiem d, nghiem de, nghiem do
sach bai » sach dao, cac bai, sach xa
bai nghe » thai nghe, van nghe, nam nghe
su sach » so sach, vu sach
nghe de » nghe det, nghe di, nghe te
de hoc » te hoc, du hoc, dien 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 sach bai nghe de hoc ) or ( thuoc sach tranh ((nghiem du) OR (nghiem dau)) hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach bai nghe de hoc ) OR ( thuoc sach tranh ((nghiem du) OR (nghiem dau)) hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach bai nghe de hoc ) or ( thuoc sach tranh ((nghiem du) OR (nghiem dau)) hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( su sach bai nghe de hoc ) or ( thuoc sach tranh ((nghiem du) OR (nghiem dau)) hoc ))*.