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