Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cham dua » chay dua, cham giua, pham duc
dua ban » dia ban, cua ban, qua ban
hoi cua » hoi chuc
hoi cuu » hoi chu, ho cuu, hoi cau
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai 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 ky nang ((mai hoi) or (dai hoc)). hieu ve cham dua ban thanh ((hoi cuu) OR (hoi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((mai hoi) OR (dai hoc)). hieu ve cham dua ban thanh ((hoi cuu) OR (hoi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((mai hoi) or (dai hoc)). hieu ve cham dua ban thanh ((hoi cuu) OR (hoi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((mai hoi) or (dai hoc)). hieu ve cham dua ban thanh ((hoi cuu) OR (hoi cua)) tre*.