Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hang vai » hang tai, hang hai, hang vi
tu sach » thu sach, su sach, te sach
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
du ban » dua ban, duc ban, du bao
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 o hoi. hieu van cac du ban ((hang vai) or (hang va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu van cac du ban ((hang vai) OR (hang va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu van cac du ban ((hang vai) or (hang va)) cua tre*.