Perhaps you should try some spelling variations:
nang noi » nang doc
nang doi » nang doc, hang doi, nang dong
cac tuc » cac toc, cac tu, cac tac
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
ve cac » va cac, vien cac
sac ky » cac ky, sai ky
thiet » thieu

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

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