Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
hanh ca » hanh cac, hanh cat, hanh cua
xuc van » duc van, luc van, vuc van
va cham » va chat, va tham
sach ty » sach y, sach tu, sach thu
mai hoi » mai khoi, dai hoi, lai hoi
ty sang » ty xang, ty hang, duy sang
cua tre » cua te, cuu tre, cua triet
ca cua » co cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty sang ((mai hoi) or (xa hoi)). hieu ((va cham) or (vien cac)) xuc van hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty sang ((mai hoi) OR (xa hoi)). hieu ((va cham) OR (vien cac)) xuc van hanh ca cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach ty sang ((mai hoi) or (xa hoi)). hieu ((va cham) or (vien cac)) xuc van hanh ca cua tre*.