Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh hai » thanh hai, nhanh hai, hang hai
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu va, hieu van
hai cuu » hai cua, hai chu, hai cuc
cuu tre » cua tre, cau tren, cau treo
cam tu » cam thu, nam tu, dam tu
thuc » thu

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 ((nang xa) or (nang x)) hoi. hieu ve ((am thuc) or (cam tu)) van hanh hai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky ((nang xa) OR (nang x)) hoi. hieu ve ((am thuc) OR (cam tu)) van hanh hai cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu cac ky ((nang xa) or (nang x)) hoi. hieu ve ((am thuc) or (cam tu)) van hanh hai cuu tre*.