Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thanh dai » thanh hai, thanh dat, thanh oai
cua viet » ca viet, hoa viet, cua vat
sang kyo » sang tao, dang ky, sang cho
duc van » duc va, duc tan, duc manh
sang ky » dang ky, tang ky, bang ky
lang xa » lang ha, dang xay, lang van
qua ca » qua cac, qua cua, qua cai
ca duc » cao duc, cua duc, ca dua

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