Perhaps you should try some spelling variations:
ban doanh » van doanh, san doanh, ban danh
thi hang » thi hanh, thi hong, thi thanh
thi nang » thi cong, ki nang, thi hanh
cac dua » cach dua, cac qua, cac du
cuu tre » cua tre, cau tren, cau treo
dua ban » dia ban, cua ban, qua ban
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
do hoai » do hoa, do hai, doi thoai
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: tu sach ((thi hang) OR (thi nang)) do hoai. hieu va cac dua ban doanh tai ((cuu tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((thi hang) OR (thi nang)) do hoai. hieu va cac dua ban doanh tai ((cuu tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thi hang) OR (thi nang)) do hoai. hieu va cac dua ban doanh tai ((cuu tre) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((thi hang) OR (thi nang)) do hoai. hieu va cac dua ban doanh tai ((cuu tre) or (cua te))*.