Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh va » thanh van, hanh va, thanh ha
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van hac » van hoc, van ha, van hai
ty nang » ky nang, ty hang, ly nang
dat ban » bat ban, da ban, day ban
hac dat » hoc dat, tac dat, hoach dat
va cua » va chua, via cua, ca cua
ma hoi » mai hoi, ma hoa, me hoi

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) OR (ty xang)) ((ma hoi) or (xa hoi)). hieu van hac dat ban thanh va cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty xang)) ((ma hoi) OR (xa hoi)). hieu van hac dat ban thanh va cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) OR (ty xang)) ((ma hoi) or (xa hoi)). hieu van hac dat ban thanh va cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) OR (ty xang)) ((ma hoi) or (xa hoi)). hieu van hac dat ban thanh va cua vat*.