Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
kham duc » pham duc, kham cuoc, pham duy
van hanh » ban hanh, van anh, van ban
su sach » vu sach
lam cua » nam cua, lam chat
vu kham » vu khanh
hieu vu » hieu va, hieu ve, hieu su
may hoi » may thoi, tay hoi, mai hoi
ty mang » ty xang, ty hang, tin mang
so sach » so sanh, bo sach, co sach
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: ((su sach) or (so sach)) ty mang may hoi. hieu vu kham duc ((van hanh) OR (van thanh)) lam cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ty mang may hoi. hieu vu kham duc ((van hanh) OR (van thanh)) lam cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) ty mang may hoi. hieu vu kham duc ((van hanh) OR (van thanh)) lam cua tre*".