Perhaps you should try some spelling variations:
trung thanh » truong thanh
thanh vai » thanh hai, thanh van, thanh tai
duc trung » dac trung, dung trung, do trung
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van bao » van ban, van dao
bao duc » dao duc, bao luc, cao duc
te sach » toc sach
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
x hoi » o hoi, x ho, 5 hoi

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) or (te sach)) y nang ((x hoi) OR (xa hoi)). hieu van bao duc trung thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (te sach)) y nang ((x hoi) OR (xa hoi)). hieu van bao duc trung thanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (te sach)) y nang ((x hoi) OR (xa hoi)). hieu van bao duc trung thanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (te sach)) y nang ((x hoi) OR (xa hoi)). hieu van bao duc trung thanh vai cua tre*.