Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
doc sac » doc sach, dac sac, hoc sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu van
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
cua te » cua tu

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

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