Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
te sach » toc sach
sach ky » sac ky, sach y, sach ty
bach tu » bach thu, cach tu, bac tu
doan vi » doan va, don vi, doan thi
cua tre » cua te, cuu tre, cua triet
dan vi » don vi, dan va, gan vi
x hoi » o hoi, x ho, 5 hoi
tu ca » tu cac, tu cua, tu can

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

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