Perhaps you should try some spelling variations:
thanh phan » thanh pho, thanh san, thanh toan
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
phan cua » nhan cua, than cua, phat cua
sach thu » sach thue, sach thieu, sach tham
duc ban » duc tan, duc van, dua ban
lam duc » lam duoc, pham duc, nam duoc
van lam » van nam
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, xach tay
x hoi » xa hoi, x ho, 5 hoi
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: su ((sach ty) OR (sach thu)) nang ((x hoi) or (o hoi)). hieu van lam duc ban thanh phan cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang ((x hoi) OR (o hoi)). hieu van lam duc ban thanh phan cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang ((x hoi) or (o hoi)). hieu van lam duc ban thanh phan cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang ((x hoi) or (o hoi)). hieu van lam duc ban thanh phan cua tre*.