Perhaps you should try some spelling variations:
thanh vien » nhan vien, thanh van
thanh ve » hanh ve, thanh va, thanh van
so sach » so sanh, bo sach, co sach
ky lang » ky dang, ky tang, tay lang
qua cac » cua cac
cac tuc » cac toc, cac tu, cac tac
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ky lang) OR (ky nang)) xa hoi. hieu qua cac tuc va ((thanh ve) or (thanh vien)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky lang) OR (ky nang)) xa hoi. hieu qua cac tuc va ((thanh ve) OR (thanh vien)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky lang) OR (ky nang)) xa hoi. hieu qua cac tuc va ((thanh ve) or (thanh vien)) cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky lang) OR (ky nang)) xa hoi. hieu qua cac tuc va ((thanh ve) or (thanh vien)) cua tre*.