Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
thanh di » thanh de, thanh do, thanh dinh
hoc dua » hoc cua, hoc duc, hoc lua
dua van » duy van, dua vao, duc van
cua tre » cua te, cuu tre, cua triet
sach ty » sach tu, sach thu, xach tay
hieu va » lieu va, hieu qua
xang x » nang x
va hoc » van hoc
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ty) OR (sach y)) xang x hoi. hieu va hoc dua van ((thanh di) or (thanh doi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ty) OR (sach y)) xang x hoi. hieu va hoc dua van ((thanh di) OR (thanh doi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ty) OR (sach y)) xang x hoi. hieu va hoc dua van ((thanh di) or (thanh doi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ty) OR (sach y)) xang x hoi. hieu va hoc dua van ((thanh di) or (thanh doi)) cua tre*.