Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
xa hanh » xa thanh, xa khanh, va hanh
y nang » ky nang, ly nang, v nang
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.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang ((x hoi) OR (o hoi)). hieu van ((luat tuc) or (luat thue)) xa hanh vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (o hoi)). hieu van ((luat tuc) OR (luat thue)) xa hanh vi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) OR (o hoi)). hieu van ((luat tuc) or (luat thue)) xa hanh vi cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) OR (o hoi)). hieu van ((luat tuc) or (luat thue)) xa hanh vi cua tu*.