Perhaps you should try some spelling variations:
dang xay » dang van, van xay
van hanh » van thanh, ban hanh, van anh
va hanh » va thanh, va danh, ban hanh
va tuan » van tuan, va quan, va toan
hieu va » lieu va, hieu qua
luu tre » luu tru, cuu tre, luy tre
lang xa » lang ha, lang van
sac ky » cac ky, sai ky
vi luu » vi lua
te sac » te sach, te cac, te san

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

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