Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van ban
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
van anh » van thanh, tuan anh, van minh
cua tre » cua te, cuu tre, cua triet
cac do » cac don, cac doi, cac du
di cua » dai cua, doi cua, de cua

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