Perhaps you should try some spelling variations:
sach tru » sach truc, sach thu, sach tu
dinh tri » chinh tri
te sach » toc sach
dinh ve » dinh ket, dinh van
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac

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

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