Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hau thuc » huu thuc, ha thuc, mau thuc
vat hanh » vat thanh, van hanh, va hanh
su sach » so sach, vu sach
van hau » van ha, van hai, van dau
cua tre » cua te, cuu tre, cua triet
y hang » ly hang, ty hang, yu hang
co hoi » co hoc
vi cua » vai cua, di cua

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 y hang ((co hoi) or (co loi)). hieu van hau thuc vat hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y hang ((co hoi) OR (co loi)). hieu van hau thuc vat hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach y hang ((co hoi) or (co loi)). hieu van hau thuc vat hanh vi cua tre*.