Perhaps you should try some spelling variations:
doanh vang » doanh van, doanh sang, doanh quang
va doanh » van doanh, vay doanh, va danh
lang van » dang van, tang van, hoang van
toc sac » toc sach, toc san, hoc sach
cua tre » cua te, cua triet, dua tren
cac toc » cac toi, cac nuoc, cac thoi
cuu tre » cau tren, cau treo
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay
sac ky » cac ky, sai ky
toc va » hoc va, toc ta, tuc va
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ky ((lang xa) or (lang van)) hoi. hieu ve cac toc va doanh vang ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky ((lang xa) OR (lang van)) hoi. hieu ve cac toc va doanh vang ((cua tre) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ky ((lang xa) or (lang van)) hoi. hieu ve cac toc va doanh vang ((cua tre) OR (cuu tre))*".