Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hang vai » hang tai, hang hai, hang vi
van cac » van hac, van cau, van bac
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
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) OR (v 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) OR (v nang)) o hoi. hieu van cac du ban ((hang vai) OR (hang va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (v 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) OR (v nang)) o hoi. hieu van cac du ban ((hang vai) or (hang va)) cua tre*.