Perhaps you should try some spelling variations:
ban doanh » van doanh, san doanh, ban danh
hieu van » hieu va, thien van, lieu va
doanh vi » doanh va, doan vi, doanh vien
can thuc » dan thuc, van thuc, cay thuc
cac thuc » cach thuc, cac thu, cay thuc
so sach » so sanh, bo sach, co sach
lang xa » lang ha, dang xay, lang van
nang ma » tang ma, sang ma, nang cao
vi cua » vai cua, di cua
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((lang xa) or (nang ma)) hoi. hieu van ((cac thuc) OR (can thuc)) ban doanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((lang xa) OR (nang ma)) hoi. hieu van ((cac thuc) OR (can thuc)) ban doanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((lang xa) or (nang ma)) hoi. hieu van ((cac thuc) OR (can thuc)) ban doanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: so sach y ((lang xa) or (nang ma)) hoi. hieu van ((cac thuc) OR (can thuc)) ban doanh vi cua te*.