Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh li » thanh loi, thanh le, nhanh li
hieu ve » hieu va, hieu van
duc ban » duc tan, duc van, dua ban
cao duc » dao duc, cao suc, giao duc
su sach » so sach
vu sach » vu bach, vu khach
cu tren » tu tren, dua tren
ve cao » va cao, ve bao, ve cac
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi
li cu » li ca, li du, le cu

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 (vu sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cao duc ban thanh li cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cao duc ban thanh li cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cao duc ban thanh li cu tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ky nang ((x hoi) OR (o hoi)). hieu ve cao duc ban thanh li cu tren*.