Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
nang noi » nang doc
nang doi » nang doc, hang doi, nang dong
dang xay » dang van, van xay
cac tuc » cac toc, cac tu, cac tac
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
lang xa » lang ha, lang van
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) OR (dang xay)) hoi. hieu va cac tuc xa ((nang doi) or (nang noi)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang xa) OR (dang xay)) hoi. hieu va cac tuc xa ((nang doi) OR (nang noi)) va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((lang xa) OR (dang xay)) hoi. hieu va cac tuc xa ((nang doi) or (nang noi)) va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang xa) OR (dang xay)) hoi. hieu va cac tuc xa ((nang doi) or (nang noi)) va triet*.