Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
vai cua » dai cua, hai cua, lai cua
loc van » luoc van, hoc van, lo van
ve cham » va cham, ve chat, vu cham
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
ve cac » va cac, vien cac

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

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