Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » vu sach
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
coc duc » hoc duc, coc luc, hoc duoc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
nang xa » nang x, lang xa, nang ma
so sach » so sanh, bo sach, co sach
vi cua » vai cua, di cua

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