Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
sach thi » sach tai, sach thieu, sach tham
hanh hai » thanh hai, nhanh hai, hang hai
ban hanh » ban hang
tham duc » pham duc, tham du, than duc
van tham » van thanh, van tuan, van chat
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
duc ban » duc tan, duc van, dua ban
hai cua » thai cua, dai cua, hoi cua
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: so ((sach thi) OR (sach thu)) nang ((x hoi) or (xa hoi)). hieu van tham duc ban hanh hai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach thi) OR (sach thu)) nang ((x hoi) OR (xa hoi)). hieu van tham duc ban hanh hai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach thi) OR (sach thu)) nang ((x hoi) or (xa hoi)). hieu van tham duc ban hanh hai cua viet".
• Adding a wildcard symbol may retrieve word variants: so ((sach thi) OR (sach thu)) nang ((x hoi) or (xa hoi)). hieu van tham duc ban hanh hai cua viet*.