Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
van bac » van ban, van bao, van hac
toc xa » tuc xa, toc ta, hoc xa
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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 bac ((toc xa) OR (hoc ma)) hanh vi cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((x hoi) OR (o hoi)). hieu van bac ((toc xa) or (hoc ma)) hanh vi cua tu~".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) OR (o hoi)). hieu van bac ((toc xa) or (hoc ma)) hanh vi cua tu*.