Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu cua » hieu qua, dieu cua, bieu cua
luoc van » luoc can, luoc va, luc van
lang van » dang van, tang van, hoang van
cac luoc » cac nuoc, cac cuoc, cac quoc
hanh di » hanh vi, hanh de, hang di
lang xa » lang ha, dang xay
di cua » dai cua, doi cua, de cua
sac ky » sai ky
cua tu » cua tuc, cua su, cua cu

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

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