Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
su sach » so sach, vu sach
ky lang » ky dang, ky tang, tay lang
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va thanh, va danh
tuc va » thuc va, truc va, tuc xa
vi va » vi van, vai va, bi va
vu va » vu van, tu va, su va

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) OR (ky nang)) xa hoi. hieu cua cac tuc va hanh ((vi va) OR (vu va)) triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) or (ky nang)) xa hoi. hieu cua cac tuc va hanh ((vi va) OR (vu va)) triet~".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) or (ky nang)) xa hoi. hieu cua cac tuc va hanh ((vi va) OR (vu va)) triet*.