Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh di » thanh doi, thanh de, thanh do
dang xay » dang van, van xay
ca viet » va viet, co viet, hoa viet
cua duc » cua tuc, cua nuoc, cua quoc
xay hoi » xa hoi, tay hoi, cay phoi
ca duc » cao duc, ca dua, ha duc
san ky » sang ky, van ky, ban ky
dan ky » van ky
di ca » di cau, di cua, doi ca

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((san ky) OR (dan ky)) dang xay hoi. hieu qua ((ca duc) or (cua duc)) van thanh di ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((san ky) OR (dan ky)) dang xay hoi. hieu qua ((ca duc) OR (cua duc)) van thanh di ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((san ky) OR (dan ky)) dang xay hoi. hieu qua ((ca duc) or (cua duc)) van thanh di ca viet".
• Adding a wildcard symbol may retrieve word variants: tu ((san ky) OR (dan ky)) dang xay hoi. hieu qua ((ca duc) or (cua duc)) van thanh di ca viet*.