Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
thi cua » thai cua, thi cuc, tri cua
dau thi » cau thi, dan thi, dao thi
cac tac » cac toc, cac bac, cac dac
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac nuoc
lang xa » lang ha, dang xay, lang van
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
y lang » o lang, _ lang, tay lang
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) OR (te sach)) y lang xa hoi. hieu va ((cac tuc) or (cac tac)) va dau thi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) y lang xa hoi. hieu va ((cac tuc) OR (cac tac)) va dau thi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) y lang xa hoi. hieu va ((cac tuc) or (cac tac)) va dau thi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) y lang xa hoi. hieu va ((cac tuc) or (cac tac)) va dau thi cua tre*.