Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
mai khoi » mai khoa, tai khoa, cac khoi
cac dat » cac dan, cai dat, cac dai
va dinh » van dinh, va kinh, va tinh
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
van cac » van hac, van cau, van bac
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
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 ky nang ((mai hoi) OR (mai khoi)). hieu van cac dat ((va hanh) or (va dinh)) vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((mai hoi) OR (mai khoi)). hieu van cac dat ((va hanh) OR (va dinh)) vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((mai hoi) OR (mai khoi)). hieu van cac dat ((va hanh) or (va dinh)) vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((mai hoi) OR (mai khoi)). hieu van cac dat ((va hanh) or (va dinh)) vi cua vat*.