Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
ban hanh » ban hang
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
cua tre » cua te, cuu tre, cua triet
xang x » nang x
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ty xang x hoi. hieu van cau duc ((va thanh) or (ban hanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty xang x hoi. hieu van cau duc ((va thanh) OR (ban hanh)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ty xang x hoi. hieu van cau duc ((va thanh) or (ban hanh)) dai cua tre*.