Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
va hanh » va thanh, va danh, ban hanh
cao luc » bao luc, cao duc, cao suc
hieu va » lieu va, hieu qua
lang ha » long ha
sai ky » sac ky
va cao » va cac, va co, va dao
dao va » dao van, tao va, do va
tu sai » tu bai, tu san, tu cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sai ky ((lang ha) or (dang xay)) hoi. hieu va cao luc ((va hanh) OR (van hanh)) dao va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sai ky ((lang ha) OR (dang xay)) hoi. hieu va cao luc ((va hanh) OR (van hanh)) dao va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sai ky ((lang ha) or (dang xay)) hoi. hieu va cao luc ((va hanh) OR (van hanh)) dao va triet".
• Adding a wildcard symbol may retrieve word variants: tu sai ky ((lang ha) or (dang xay)) hoi. hieu va cao luc ((va hanh) OR (van hanh)) dao va triet*.