Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh hai » thanh phan, thanh hoa, thanh san
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
hang xa » hoang xa, hang va, hang ca
hieu va » hieu qua
cac cuc » cac cuoc, cac cua, cac nuoc
cuc ban » cua ban, cac ban, cuu ban
cua tre » cua te, cuu tre, cua triet

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 ty hang xa hoi. ((hieu va) OR (lieu va)) cac cuc ban thanh hai ((cua tre) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty hang xa hoi. ((hieu va) OR (lieu va)) cac cuc ban thanh hai ((cua tre) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty hang xa hoi. ((hieu va) OR (lieu va)) cac cuc ban thanh hai ((cua tre) or (cua viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty hang xa hoi. ((hieu va) OR (lieu va)) cac cuc ban thanh hai ((cua tre) or (cua viet))*.