Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh hai » thanh hai, nhanh hai, hang hai
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu van
hieu va » lieu va, hieu qua
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
cac vo » cac co, cac vi, cac bo

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((nang xa) OR (nang x)) hoi. ((hieu ve) or (hieu va)) cac vo van hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (nang x)) hoi. ((hieu ve) OR (hieu va)) cac vo van hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) OR (nang x)) hoi. ((hieu ve) or (hieu va)) cac vo van hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) OR (nang x)) hoi. ((hieu ve) or (hieu va)) cac vo van hanh hai cua tre*.