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

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