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