Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hang vai » hang va, hang tai, hang hai
ban hang » ngan hang
hieu van » hieu va, thien van, lieu va
dua ban » dia ban, cua ban, qua ban
cua tre » cua te, cuu tre, dua tren
tu sach » thu sach, su sach, te sach
cac dua » cach dua, cac qua, cac du
van cac » van hac, van cau, van bac
y nang » ky nang, ly nang, v nang
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.

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