Perhaps you should try some spelling variations:
hanh vai » hanh va, hanh tai, hanh van
hieu van » hieu va, thien van, lieu va
su sach » vu sach
van cac » van hac, van cau, van bac
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
cac bo » bac bo, cac co
x hoi » xa hoi, o hoi, x ho
bo va » bao va, do va, so va

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) or (so sach)) ky nang x hoi. hieu van cac bo va ((hanh vai) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky nang x hoi. hieu van cac bo va ((hanh vai) OR (hanh vi)) cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) ky nang x hoi. hieu van cac bo va ((hanh vai) or (hanh vi)) cua tre*.