Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, hieu ve
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, dua tren
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 van) OR (lieu va)) cac duc van hanh va ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu van) OR (lieu va)) cac duc van hanh va ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu van) OR (lieu va)) cac duc van hanh va ((cua tre) or (cua triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu van) OR (lieu va)) cac duc van hanh va ((cua tre) or (cua triet))*.