Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
day thanh » dao thanh, dat thanh, da thanh
thuoc day » thuc day, thuoc dac, thuoc dang
nam thuoc » nam thuc, nam thu, nha thuoc
hieu van » hieu va, thien van, lieu va
lang van » dang van, tang van, hoang van
doi cua » dai cua, hoi cua
sach ky » sac ky, sach ty, sach kem
lang xa » lang ha, dang xay
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((sach ky) or (sach y)) ((lang xa) OR (lang van)) hoi. hieu van nam thuoc day thanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach y)) ((lang xa) OR (lang van)) hoi. hieu van nam thuoc 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) OR (lang van)) hoi. hieu van nam thuoc day thanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) or (sach y)) ((lang xa) OR (lang van)) hoi. hieu van nam thuoc day thanh doi cua tre*.