Perhaps you should try some spelling variations:
thanh vien » nhan vien
thanh van » thanh san, thanh toan, thanh phan
hieu cua » hieu qua, dieu cua, bieu cua
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
cac toc » cac toi, cac nuoc, cac thoi
sach ky » sac ky, sach y, sach ty
cac tuc » cac tu, cac tac, cac nuoc
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang

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