Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
xa hanh » xa thanh, xa khanh, va hanh
cac tac » cac toc, cac bac, cac dac
cac tuc » cac toc, cac tu, cac nuoc
sach ky » sac ky, sach y, sach ty
vi cua » vai cua, di cua
cua te » cua tu
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (o hoi)). hieu van ((cac tuc) OR (cac tac)) xa hanh vi cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((x hoi) or (o hoi)). hieu van ((cac tuc) OR (cac tac)) xa hanh vi cua te~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (o hoi)). hieu van ((cac tuc) OR (cac tac)) xa hanh vi cua te*.