Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
cac dac » cac dan, cac dai, cac bac
dinh vi » dinh ve, dinh viet, dinh tri
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, xach tay
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
dac va » duc va, day va, dat va

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 ty) OR (sach thu)) nang xa hoi. hieu ve cac dac va ((dinh vi) OR (dinh ket)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach thu)) nang xa hoi. hieu ve cac dac va ((dinh vi) or (dinh ket)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach thu)) nang xa hoi. hieu ve cac dac va ((dinh vi) or (dinh ket)) cua tre*.