Perhaps you should try some spelling variations:
sach tham » sach nha
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
bang xa » bang va, mang xa, ang xa
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
van am » van nam, van lam, van dam

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach tham ((bang xa) or (lang xa)) hoi. hieu van am thuc ((va dan) OR (ca dan)) sai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach tham ((bang xa) OR (lang xa)) hoi. hieu van am thuc ((va dan) OR (ca dan)) sai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach tham ((bang xa) or (lang xa)) hoi. hieu van am thuc ((va dan) OR (ca dan)) sai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach tham ((bang xa) or (lang xa)) hoi. hieu van am thuc ((va dan) OR (ca dan)) sai cua tre*.