Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
te sach » toc sach
lang xa » lang ha, lang van
cua tec » cua tuc, cua toc, cua viec
hieu ve » hieu va, hieu van
hanh di » hanh vi, hanh de, hang di
cac tuc » cac toc, cac tu, cac tac
tuc van » thuc van, truc van, tuc va
ve cac » va cac, vien cac
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach y ((lang xa) or (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tec) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y ((lang xa) OR (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tec) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: te sach y ((lang xa) or (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tec) or (cua te))*.