Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
cua chu » sua chua
va cua » va chua, via cua, ca cua
o hoi » co hoi, o hoc, o hai

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 xang ((xa hoi) or (o hoi)). hieu va cac duc van hanh va cua chu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty xang ((xa hoi) OR (o hoi)). hieu va cac duc van hanh va cua chu.
• Adding a wildcard symbol may retrieve word variants: su sach ty xang ((xa hoi) or (o hoi)). hieu va cac duc van hanh va cua chu*.