Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac xuc » cam xuc, cac nuoc, chat xuc
xuc van » duc van, luc van, vuc van
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hai

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 ky nang ((o hoi) or (co hoc)). hieu ve cac xuc van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((o hoi) OR (co hoc)). hieu ve cac xuc van hanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((o hoi) or (co hoc)). hieu ve cac xuc van hanh tai cua tre*.