Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thu sach » tu sach, thuat sach, thuoc sach
vien cac » vien bach, vien dai, vien da
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
cac tu » cac thu, cach tu, cac du
dan vi » doan vi, don vi, gan vi
dan va » doan va, dan ca, ban va
5 hoi » o hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((5 hoi) or (xa hoi)). hieu vien cac tu va ((dan vi) OR (dan va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((5 hoi) OR (xa hoi)). hieu vien cac tu va ((dan vi) OR (dan va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((5 hoi) or (xa hoi)). hieu vien cac tu va ((dan vi) OR (dan va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((5 hoi) or (xa hoi)). hieu vien cac tu va ((dan vi) OR (dan va)) cua tre*.