Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
thanh tai » thanh toan, doanh tai, thanh san
cac cach » cai cach, cuoc cach, va cach
cach ban » cac ban, cach bao, cach ben
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van cac » van hac, van cau, van bac
nang ro » nang co, nang ho, nang ra
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang x

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) OR (nang ro)) hoi. hieu van cac 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) OR (nang ro)) hoi. hieu van cac 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) OR (nang ro)) hoi. hieu van cac cach ban ((thanh tai) or (thanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang o) OR (nang ro)) hoi. hieu van cac cach ban ((thanh tai) or (thanh hai)) cua tre*.