Perhaps you should try some spelling variations:
doanh ban » doanh bat, doanh nhan, doanh luan
doanh van » doan van, doanh va, doanh nhan
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang xa hoi. ((hieu ve) or (hieu van)) pham duc va ((doanh ban) OR (doanh van)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. ((hieu ve) OR (hieu van)) pham duc va ((doanh ban) OR (doanh van)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. ((hieu ve) or (hieu van)) pham duc va ((doanh ban) OR (doanh van)) cua tre*".