Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
dung doi » huong doi, dung tai, dung co
nong doi » vong doi, nong do, dong doi
cac tuc » cac toc, cac tu, cac tac
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
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.

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