Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach ty » sach tu, sach thu, xach tay
mai hoi » mai khoi, dai hoi, lai hoi
van hac » van hoc, van ha, van hai
hac dat » hoc dat, tac dat, hoach dat
va hanh » van hanh, va thanh, va danh
ma hoi » xa hoi, ma hoa, me hoi
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: tu ((sach y) or (sach ty)) nang ((ma hoi) or (mai hoi)). hieu van hac dat va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach y) OR (sach ty)) nang ((ma hoi) OR (mai hoi)). hieu van hac dat va hanh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: tu ((sach y) or (sach ty)) nang ((ma hoi) or (mai hoi)). hieu van hac dat va hanh vi cua vat*.