Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
thi cong » tai cong, thien cong
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
tham duc » pham duc, tham du, than duc
ban hanh » ban hang
hanh lai » hanh lam, hanh tai, thanh lap
cua viet » ca viet, hoa viet, cua vat
so sach » so sanh, bo sach, co sach
duc ban » duc tan, duc van, dua ban
lai cua » dai cua, hai cua, lai chau
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 cong ((x hoi) or (xa hoi)). hieu van tham duc ban hanh lai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach thi cong ((x hoi) OR (xa hoi)). hieu van tham duc ban hanh lai cua viet.
• Adding a wildcard symbol may retrieve word variants: so sach thi cong ((x hoi) or (xa hoi)). hieu van tham duc ban hanh lai cua viet*.