Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam tu
thanh de » hanh de, thanh ve, thanh do
sach ky » sach y, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
de cua » le cua, te cua, dieu cua
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: te ((sach ky) OR (sac ky)) nang x hoi. hieu van ((nam thuc) or (nam thu)) ban thanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sac ky)) nang x hoi. hieu van ((nam thuc) OR (nam thu)) ban thanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) OR (sac ky)) nang x hoi. hieu van ((nam thuc) or (nam thu)) ban thanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) OR (sac ky)) nang x hoi. hieu van ((nam thuc) or (nam thu)) ban thanh de cua tre*.