Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh hai » thanh hai, nhanh hai, hang hai
sang xa » song xa, lang xa, mang xa
sang ma » tang ma, nang ma, sang tao
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
hai cua » thai cua, dai cua, hoi cua
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 cac duc van hanh hai 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 cac duc van hanh hai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu cac ky ((sang xa) or (sang ma)) hoi. hieu va cac duc van hanh hai cua tre*.