Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
van bac » van ban, van bao, van hac
bac dat » bac dai, ban dat, bac dan
dat ban » bat ban, da ban, day ban
vai cua » dai cua, hai cua, lai cua
vi 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 ((ma hoa) or (mai hoi)). hieu van bac dat ban thanh ((vi cua) OR (vai cua)) vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((ma hoa) OR (mai hoi)). hieu van bac dat ban thanh ((vi cua) OR (vai cua)) vat*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((ma hoa) or (mai hoi)). hieu van bac dat ban thanh ((vi cua) OR (vai cua)) vat*".