Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
hanh vai » hanh va, hanh tai, hanh van
tu sach » thu sach, su sach, te sach
so sach » so sanh, bo sach, co sach
cac cao » cac co, ca cao, bac cao
cua tre » cua te, cuu tre, cua triet
cao va » cao van, tao va, co va

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: ((tu sach) OR (so sach)) ky nang x ho. hieu vien cac cao va ((hanh vai) OR (hanh vi)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (so sach)) ky nang x ho. hieu vien cac cao va ((hanh vai) OR (hanh vi)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (so sach)) ky nang x ho. hieu vien cac cao va ((hanh vai) OR (hanh vi)) cua tre*.