Perhaps you should try some spelling variations:
thuoc ban » thuoc tan, thuoc dang, thu ban
nam thuoc » nam thuc, nam thu, nha thuoc
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
su sach » so sach
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
vu nang » vuc nang, va nang, vu dang
vu sach » vu bach, vu khach
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho
o hai » co hai, so hai, o lai

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 (vu sach)) vu nang ((x hoi) or (o hai)). hieu van nam thuoc ban hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) vu nang ((x hoi) OR (o hai)). hieu van nam thuoc ban hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) vu nang ((x hoi) or (o hai)). hieu van nam thuoc ban hanh di cua tre*.