Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
toc sach » hoc sach, doc sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
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, x ho, 5 hoi
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: toc sach ky nang ((x hoi) or (o hoi)). 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: toc sach ky nang ((x hoi) OR (o hoi)). hieu ve cac nuoc va hanh vi ((cua tre) OR (cua triet)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((x hoi) or (o hoi)). hieu ve cac nuoc va hanh vi ((cua tre) or (cua triet))*.