Perhaps you should try some spelling variations:
thanh de » hanh de, thanh ve, thanh do
thanh di » thanh doi, thanh do, thanh dinh
te sach » toc sach
cac toc » cac toi, cac nuoc, cac thoi
cua tre » cua te, cuu tre, cua triet
cac loc » cac lop, cac hoc, cac nuoc
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
sach 7 » sach y, sach 2
ma hoi » mai hoi, xa hoi, ma hoa
7 tang » 6 tang

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach 7 tang ma hoi. hieu va ((cac loc) OR (cac toc)) va ((thanh di) or (thanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach 7 tang ma hoi. hieu va ((cac loc) OR (cac toc)) va ((thanh di) OR (thanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach 7 tang ma hoi. hieu va ((cac loc) OR (cac toc)) va ((thanh di) or (thanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach 7 tang ma hoi. hieu va ((cac loc) OR (cac toc)) va ((thanh di) or (thanh de)) cua tre*.