Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
hieu ve » hieu va
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
y tang » ky tang, 6 tang, 7 tang
ma hoi » mai hoi, xa hoi, ma hoa
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 tang ma hoi. ((hieu ve) OR (hieu van)) cac duc van hanh vi cua vat~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y tang ma hoi. ((hieu ve) OR (hieu van)) cac duc van hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach y tang ma hoi. ((hieu ve) OR (hieu van)) cac duc van hanh vi cua vat*.