Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh di » thanh doi, thanh de, thanh do
cua viet » ca viet, hoa viet, cua vat
tang xa » trang xa, tang ma, tang ha
lang xa » lang ha, dang xay, lang van
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
tu can » tu ban, tu cac, thu canh
can ky » van ky, dan ky, ban ky
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu can ky ((tang xa) or (lang xa)) hoi. hieu qua cac duc van thanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu can ky ((tang xa) OR (lang xa)) hoi. hieu qua cac duc van thanh di cua viet.
• Adding a wildcard symbol may retrieve word variants: tu can ky ((tang xa) or (lang xa)) hoi. hieu qua cac duc van thanh di cua viet*.