Perhaps you should try some spelling variations:
ban doanh » van doanh, san doanh, ban danh
ban hanh » ban hang
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
cai cuu » cap cuu, cham cuu
hieu va » lieu va, hieu qua
lang xa » lang ha, lang van
cua tre » cua te, cuu tre, cua triet
va cai » va cac, va bai, va dai
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 y ((lang xa) OR (dang xay)) hoi. hieu va cai cuu ((ban doanh) or (ban hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((lang xa) OR (dang xay)) hoi. hieu va cai cuu ((ban doanh) OR (ban hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((lang xa) OR (dang xay)) hoi. hieu va cai cuu ((ban doanh) or (ban hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((lang xa) OR (dang xay)) hoi. hieu va cai cuu ((ban doanh) or (ban hanh)) vi cua tre*.