Perhaps you should try some spelling variations:
thanh hoi » thanh hoai, thanh hoa, thanh hai
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
ly hang » ly quang
van cam » van nam, van lam, van cau
dua ban » dia ban, cua ban, qua ban
hoi cua » hoi chuc
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

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 ((y nang) or (ly hang)) xa hoi. hieu van cam ((dua ban) or (duc va)) thanh hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (ly hang)) xa hoi. hieu van cam ((dua ban) OR (duc va)) thanh hoi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) or (ly hang)) xa hoi. hieu van cam ((dua ban) or (duc va)) thanh hoi cua tre*.