Perhaps you should try some spelling variations:
thanh de » hanh de, thanh ve, thanh do
thanh di » thanh doi, thanh do, thanh dinh
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
cuc ban » cua ban, cac ban, cuu ban
cac cuc » cac cuoc, cac cua, cac nuoc
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet

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: su sach ty ((lang xa) OR (nang x)) hoi. hieu va cac cuc ban ((thanh di) OR (thanh de)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((lang xa) or (nang x)) hoi. hieu va cac cuc ban ((thanh di) OR (thanh de)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((lang xa) or (nang x)) hoi. hieu va cac cuc ban ((thanh di) OR (thanh de)) cua tre*.