Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
cac duc » cao duc, cac dac, cac nuoc
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
ty hang » ly hang, thi hang, thu hang
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 ((ty hang) OR (ty xang)) x hoi. hieu van ((cac duc) or (cac du)) va thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty hang) OR (ty xang)) x hoi. hieu van ((cac duc) OR (cac du)) va thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty hang) OR (ty xang)) x hoi. hieu van ((cac duc) or (cac du)) va thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((ty hang) OR (ty xang)) x hoi. hieu van ((cac duc) or (cac du)) va thanh dai cua tre*.