Perhaps you should try some spelling variations:
nang doi » nang doc, hang doi, nang dong
nang noi » nang doc
va triet » va trien, ve triet, cua triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
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: tu sach ky tang xa hoi. hieu va cac tuc xa ((nang doi) OR (nang noi)) ((va triet) OR (va thiet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky tang xa hoi. hieu va cac tuc xa ((nang doi) or (nang noi)) ((va triet) OR (va thiet))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. hieu va cac tuc xa ((nang doi) or (nang noi)) ((va triet) OR (va thiet))*.