Perhaps you should try some spelling variations:
hanh hai » thanh hai, nhanh hai, hang hai
cua tre » cua te, cuu tre, cua triet
hai cua » thai cua, dai cua, hoi cua
va hanh » van hanh, va thanh, va danh
cac duc » cac du, cao duc, cac dac
qua cac » cua cac
sang ma » tang ma, nang ma, sang tao
sang xa » song xa, lang xa, mang xa
sang ky » sang kyo, dang ky, tang ky
san ky » van ky, dan ky, ban 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 ((san ky) OR (sang ky)) ((sang xa) or (sang ma)) hoi. hieu qua cac duc va hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((san ky) OR (sang ky)) ((sang xa) OR (sang ma)) hoi. hieu qua cac duc va hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((san ky) OR (sang ky)) ((sang xa) or (sang ma)) hoi. hieu qua cac duc va hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((san ky) OR (sang ky)) ((sang xa) or (sang ma)) hoi. hieu qua cac duc va hanh hai cua tre*.