Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
ban thanh » ban hanh, ban hang
sach thu » sach thue, sach thieu, sach tham
cac duc » cac du, cao duc, cac dac
cuu tre » cua tre, cau tren, cau treo
duc ban » duc tan, duc van, dua ban
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, xach tay
do hoai » do hoa, do hai, doi thoai
hang do » hang doi, dang do, hang di
ve cac » va cac, vien cac
cua te » cua tu

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 ty) OR (sach thu)) hang do hoai. hieu ve cac duc ban thanh tai ((cuu tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) hang do hoai. hieu ve cac duc ban thanh tai ((cuu tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) hang do hoai. hieu ve cac duc ban thanh tai ((cuu tre) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) hang do hoai. hieu ve cac duc ban thanh tai ((cuu tre) or (cua te))*.