Perhaps you should try some spelling variations:
thanh do » thanh de, thanh pho, thanh hoa
thanh di » thanh doi, thanh de, thanh dinh
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
sach 5 » sach y, sach 2
cam lo » nam lo, cam ly, cam o
ma hoi » mai hoi, xa hoi, ma hoa
5 tang » 6 tang, 7 tang

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: te sach 5 tang ma hoi. hieu va ((cam loc) OR (cam lo)) va ((thanh di) OR (thanh do)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach 5 tang ma hoi. hieu va ((cam loc) or (cam lo)) va ((thanh di) OR (thanh do)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach 5 tang ma hoi. hieu va ((cam loc) or (cam lo)) va ((thanh di) OR (thanh do)) cua tre*.