Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
co sach » bo sach, cuon sach, hoc sach
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
dai lo » dai so, dai ly, dai ho
dai o » dai so, dao o, dai 2
x hoi » xa hoi, o hoi, x ho

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: co sach ky nang x hoi. hieu vien ((dai lo) OR (dai o)) ((va danh) OR (va hanh)) dai cua tre~.
• Adding a wildcard symbol may retrieve word variants: co sach ky nang x hoi. hieu vien ((dai lo) or (dai o)) ((va danh) or (va hanh)) dai cua tre*.