Perhaps you should try some spelling variations:
de triet » ve triet, de thiet, su triet
van hanh » van thanh, ban hanh, van anh
lang van » dang van, tang van, hoang van
va hanh » va thanh, va danh, ban hanh
cac thu » cach thuc, cac thoi
sach ky » sac ky, sach y, sach ty
so sach » so sanh, bo sach, co sach
lang xa » lang ha, dang xay
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
va de » va do, va le

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

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