Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
chat tuc » chat xuc, luat tuc, chat huu
dinh vi » dinh ve, dinh viet, dinh tri
ve chat » va chat, van chat
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
nang xa » lang xa, nang ma, mang xa
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

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

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