Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
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
bai cua » ban cua, dai cua, bai ca
hai cua » thai cua, dai cua, hoi cua
ve cac » va cac, vien cac

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

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