Perhaps you should try some spelling variations:
doanh cua » doanh luan
hieu van » hieu va, thien van, lieu va
toc sach » hoc sach, doc sach, thuoc sach
cua cua » cua chua, ca cua, qua cua
nang xa » nang x, lang xa, nang ma
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc va
loc va » hoc va, luc va

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) OR (toc sach)) ky nang xa hoi. hieu van cau ((xuc va) or (loc va)) doanh cua cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang xa hoi. hieu van cau ((xuc va) OR (loc va)) doanh cua cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky nang xa hoi. hieu van cau ((xuc va) or (loc va)) doanh cua cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang xa hoi. hieu van cau ((xuc va) or (loc va)) doanh cua cua tre*.