Perhaps you should try some spelling variations:
duc thuan » duc tan, duc phan, duc thanh
duc thang » duc tan, duc hung
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua
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 ky nang x hoi. ((hieu ve) or (lieu va)) cam ((duc thuan) OR (duc thang)) anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang x hoi. ((hieu ve) OR (lieu va)) cam ((duc thuan) OR (duc thang)) anh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang x hoi. ((hieu ve) or (lieu va)) cam ((duc thuan) OR (duc thang)) anh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang x hoi. ((hieu ve) or (lieu va)) cam ((duc thuan) OR (duc thang)) anh vi cua tre*.