Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hanh dai » hanh tai, hanh dao, vanh dai
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
cac thu » cach thuc, cac thoi
sach ky » sac ky, sach y, sach ty
su sach » so sach, vu sach
dang xa » lang xa, dang ha, dang va
hieu va » lieu va, hieu qua
cac tu » cach tu, cac du, tac tu
dai va » mai va

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

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