Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
nang doc » nang luc
sach ky » sac ky, sach y, sach ty
cac tuc » cac toc, cac tu, cac tac
tu sach » thu sach, su sach, te sach
hieu ve » hieu van
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
hieu va » lieu va, hieu qua

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

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