Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
hang vi » hang va, hanh vi, hang di
duc van » duc va, duc tan, duc manh
van cam » van nam, van lam, van cau
ly hang » ly quang
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ((ly hang) or (ty xang)) xa hoi. hieu van cam ((quoc ban) or (duc van)) hang vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ((ly hang) OR (ty xang)) xa hoi. hieu van cam ((quoc ban) OR (duc van)) hang vi cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ((ly hang) or (ty xang)) xa hoi. hieu van cam ((quoc ban) or (duc van)) hang vi cua tre*.