Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, dua tren
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho
o hoc » co hoc, mo hoc, so hoc

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

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