Perhaps you should try some spelling variations:
ban hang » ngan hang
tu sach » thu sach, su sach, te sach
hieu ve » hieu van
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
duc ban » duc tan, duc van, dua ban
vai cua » hai cua, lai cua, bai cua
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach v nang x hoi. ((hieu ve) OR (hieu va)) cac duc ban hang ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach v nang x hoi. ((hieu ve) OR (hieu va)) cac duc ban hang ((vai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach v nang x hoi. ((hieu ve) OR (hieu va)) cac duc ban hang ((vai cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach v nang x hoi. ((hieu ve) OR (hieu va)) cac duc ban hang ((vai cua) or (dai cua)) tre*.