Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
van thanh » ban thanh, van tuan
cua viet » ca viet, hoa viet, cua vat
sang ky » sang kyo, dang ky, bang ky
lang xa » lang ha, dang xay, lang van
tang ky » dang ky, trong ky, tang khu
ca duc » cao duc, cua duc, ha duc
ca dua » cay dua, ca cua, ca da

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

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