Perhaps you should try some spelling variations:
ban hanh » ban hang
sanh ky » hanh ky, nganh ky, thanh ky
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
cac duc » cac du, cao duc, cac dac
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
sang ky » sang kyo, dang ky, tang ky
cua tre » cua te, cuu tre, cua triet

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 (sang ky)) lang xa hoi. hieu va cac duc ((ban hanh) or (va danh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sanh ky) OR (sang ky)) lang xa hoi. hieu va cac duc ((ban hanh) OR (va danh)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sanh ky) OR (sang ky)) lang xa hoi. hieu va cac duc ((ban hanh) or (va danh)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: so ((sanh ky) OR (sang ky)) lang xa hoi. hieu va cac duc ((ban hanh) or (va danh)) vai cua tre*.