Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
bach ky » bac ky
ky tang » ky nang, ky dang, kho tang
va hanh » va thanh, va danh, ban hanh
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
hieu le » hieu he, hieu ly, tieu le
doi cua » dai cua, hoi cua
na thu » nam thu, va thu, ma thu
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu bach ky tang ma hoi. ((hieu le) or (hieu ve)) na thu ((va hanh) OR (van hanh)) doi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu bach ky tang ma hoi. ((hieu le) OR (hieu ve)) na thu ((va hanh) OR (van hanh)) doi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu bach ky tang ma hoi. ((hieu le) or (hieu ve)) na thu ((va hanh) OR (van hanh)) doi cua vat".
• Adding a wildcard symbol may retrieve word variants: vu bach ky tang ma hoi. ((hieu le) or (hieu ve)) na thu ((va hanh) OR (van hanh)) doi cua vat*.