Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
co sach » bo sach, cuon sach, hoc sach
va dinh » van dinh, va kinh, va tinh
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
dai ho » dai hoc, dai hoi, dai hoa
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.

• Performing a fuzzy search may retrieve terms with similar spellings: co sach ky nang x hoi. hieu vien ((dai ho) or (dai o)) ((va dinh) or (va hanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach ky nang x hoi. hieu vien ((dai ho) OR (dai o)) ((va dinh) OR (va hanh)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: co sach ky nang x hoi. hieu vien ((dai ho) or (dai o)) ((va dinh) or (va hanh)) dai cua tre*.