Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
nam thuoc » nam thuc, nha thuoc, cay thuoc
thanh doi » thanh loi, thanh moi, thanh do
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach ty, sach kem
lang xa » lang ha, dang xay, lang van
doi cua » dai cua, hoi cua
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: toc ((sach ky) OR (sach y)) lang xa hoi. hieu van ((nam thuoc) OR (nam thu)) day thanh doi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ky) or (sach y)) lang xa hoi. hieu van ((nam thuoc) OR (nam thu)) day thanh doi cua tre~".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) or (sach y)) lang xa hoi. hieu van ((nam thuoc) OR (nam thu)) day thanh doi cua tre*.