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 » thien van, lieu va, hieu ve
tu sach » thu sach, su sach, tu cach
hieu va » lieu va, hieu qua
vai cua » dai cua, hai cua, lai cua
bao duc » dao duc, bao luc, cao duc
cua tre » cua te, cuu tre, cua triet
lo nang » ho nang, ly nang, loai nang
te sach » toc sach

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