Perhaps you should try some spelling variations:
thieu nien » thien nhien
cua triet » cua viet, su triet, va triet
hieu hien » bieu hien, dieu hien, chieu chien
hanh vai » hanh vi, hanh va, hanh tai
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
cac tu » cac thu, cach tu, cac du
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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 o hoi. ((thieu nien) or (hieu hien)) cac tu va hanh vai ((cua triet) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. ((thieu nien) OR (hieu hien)) cac tu va hanh vai ((cua triet) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hoi. ((thieu nien) or (hieu hien)) cac tu va hanh vai ((cua triet) or (cuu tre))*.