Perhaps you should try some spelling variations:
thanh tai » thanh toan, doanh tai, thanh san
thanh hai » thanh phan, thanh hoa, thanh san
sach ty » sach y, sach thu, xach tay
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
sach tu » sach thu, cach tu, sach uu
cuu va » cuu van, cuu ve
ve cap » ve cac, le cap, ve cai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so ((sach ty) OR (sach tu)) nang cao hoi. hieu ve cap cuu va ((thanh hai) or (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ty) OR (sach tu)) nang cao hoi. hieu ve cap cuu va ((thanh hai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ty) OR (sach tu)) nang cao hoi. hieu ve cap cuu va ((thanh hai) or (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: so ((sach ty) OR (sach tu)) nang cao hoi. hieu ve cap cuu va ((thanh hai) or (thanh tai)) cua tre*.