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