Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cac thu » cach thuc, cac thoi
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
va dan » ca dan, va dau, va dap
va dao » ca dao
di cua » dai cua, doi cua, de cua
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: tu sach ky nang x hoi. hieu ve ((cac thu) or (cac du)) ((va dan) OR (va dao)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu ve ((cac thu) OR (cac du)) ((va dan) OR (va dao)) di cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu ve ((cac thu) or (cac du)) ((va dan) OR (va dao)) di cua tre*".