Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
so sanh » do sanh
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
cac tac » cac toc, cac bac, cac dac
tac van » tac vang, cac van, tac va
sanh y » sinh y, anh y, hanh y
ve cac » va cac, vien cac
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sanh y ((nang xa) or (lang xa)) hoi. hieu ve cac tac van hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh y ((nang xa) OR (lang xa)) hoi. hieu ve cac tac van hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: so sanh y ((nang xa) or (lang xa)) hoi. hieu ve cac tac van hanh vi cua viet*.