Perhaps you should try some spelling variations:
nganh ky » nganh y, nganh xay, hanh ky
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va
sanh ky » hanh ky, sang ky, thanh ky
tang xa » trang xa, tang ma, lang xa
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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

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