Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
quan van » quan va, quan luan, quan doan
van cuu » van cau, van chu, van cu
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
luan » lan

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y nang ((xa hoi) or (ma hoa)). hieu van nam ((quan van) OR (luan van)) thanh van cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((xa hoi) OR (ma hoa)). hieu van nam ((quan van) OR (luan van)) thanh van cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((xa hoi) or (ma hoa)). hieu van nam ((quan van) OR (luan van)) thanh van cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((xa hoi) or (ma hoa)). hieu van nam ((quan van) OR (luan van)) thanh van cuu tre*.