Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
ban thanh » ban hanh, ban hang
sach thi » sach thu, sach tai, sach thieu
tu sach » thu sach, su sach, te sach
cuu tre » cua tre, cau tren, cau treo
hang do » hang doi, dang do, hang di
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
duc ban » duc tan, duc van, dua ban
ve cac » va cac, vien cac
hang o » hang o2, hoang o, thang o
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi ((hang o) OR (hang do)) hoi. 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 thi ((hang o) OR (hang do)) hoi. hieu ve cac duc ban thanh tai ((cuu tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: tu sach thi ((hang o) OR (hang do)) hoi. hieu ve cac duc ban thanh tai ((cuu tre) or (cua te))*.