Perhaps you should try some spelling variations:
cach su » cach tu, hoach su
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
cac su » cac sau, cac du, cac tu
va dao » ca dao
dao vi » dao voi, dao ve, dao va
vi cuu » vi luu, vinh cuu
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) or (sac ky)) nang o hoi. hieu ve ((cac su) OR (cach su)) va dao vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang o hoi. hieu ve ((cac su) OR (cach su)) va dao vi cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang o hoi. hieu ve ((cac su) OR (cach su)) va dao vi cuu tre*".