Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hanh cac » hang cac, hanh cat, nhanh cay
so sach » so sanh, bo sach, co sach
cac cua » cach cua, cac qua, ca cua
va hanh » van hanh, va thanh, va danh
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
xuc va » duc va, tuc va, luc va

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 va hanh cac 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 va hanh cac 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 va hanh cac cua tre*.