Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
chat duc » chat xuc, chat doc, chet duoc
va triet » va thiet, va trien, ve triet
cua viet » ca viet, hoa viet, cua vat
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang xa hoi. ((hieu van) OR (hieu va)) chat duc va hanh vi ((va triet) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang xa hoi. ((hieu van) OR (hieu va)) chat duc va hanh vi ((va triet) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang xa hoi. ((hieu van) OR (hieu va)) chat duc va hanh vi ((va triet) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang xa hoi. ((hieu van) OR (hieu va)) chat duc va hanh vi ((va triet) or (cua viet))*.