Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hanh vai » hanh va, hanh tai, hanh van
pham duy » pham duc
lang van » dang van, tang van, hoang van
duy ban » uy ban, duy van, duy can
dang ky » dang y, dan ky, dong ky
tu dang » thu dang, tu dong, su dang
lang xa » lang ha, dang xay
v pham » vi pham, d pham
hieu v » hieu va, hieu ve, hieu 2

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu dang ky ((lang xa) or (lang van)) hoi. hieu v pham duy ban ((hanh vai) OR (hanh vi)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu dang ky ((lang xa) OR (lang van)) hoi. hieu v pham duy ban ((hanh vai) OR (hanh vi)) cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu dang ky ((lang xa) or (lang van)) hoi. hieu v pham duy ban ((hanh vai) OR (hanh vi)) cua viet".
• Adding a wildcard symbol may retrieve word variants: tu dang ky ((lang xa) or (lang van)) hoi. hieu v pham duy ban ((hanh vai) OR (hanh vi)) cua viet*.