Perhaps you should try some spelling variations:
tang thanh » dang thanh, trung thanh, hoang thanh
thanh vai » thanh hai, thanh van, thanh tai
duc tang » duc thang, duc tan, tuc tang
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, tu cach
bao duc » dao duc, bao luc, cao duc
cua tre » cua te, cua triet, dua tren
van bao » van ban, van dao
lo nang » ho nang, ly nang, loai nang
te sach » toc sach
cuu tre » cau tren, cau treo
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: ((tu sach) or (te sach)) lo nang x hoi. hieu van bao duc tang thanh vai ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) lo nang x hoi. hieu van bao duc tang thanh vai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) lo nang x hoi. hieu van bao duc tang thanh vai ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) lo nang x hoi. hieu van bao duc tang thanh vai ((cua tre) OR (cuu tre))*.