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