Perhaps you should try some spelling variations:
su sach » vu sach
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
ty van » ly van, ta van
va lam » van lam, va lap
loc va » luc va
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)) ty van xay hoi. hieu va lam ((loc va) or (hoc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ty van xay hoi. hieu va lam ((loc va) OR (hoc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ty van xay hoi. hieu va lam ((loc va) or (hoc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) ty van xay hoi. hieu va lam ((loc va) or (hoc va)) hanh vi cua tre*.