Perhaps you should try some spelling variations:
thanh tai » thanh toan, doanh tai, thanh san
thanh hai » thanh phan, thanh hoa, thanh san
hieu van » hieu va, thien van, lieu va
cac cach » cuoc cach, va cach, cac bac
cai cach » loi cach, tai cac, va cach
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
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 cach) OR (cai cach)) ban ((thanh tai) or (thanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu van ((cac cach) OR (cai cach)) ban ((thanh tai) OR (thanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang o hoi. hieu van ((cac cach) OR (cai cach)) ban ((thanh tai) or (thanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu van ((cac cach) OR (cai cach)) ban ((thanh tai) or (thanh hai)) cua tre*.