Perhaps you should try some spelling variations:
sach tham » sach nha
tham nang » nham nang, tham lang, tham nhung
than duc » tran duc, phan duc, than doc
cua viet » ca viet, cua vat, cua dieu
hanh lai » hanh lam, hanh tai, thanh lap
ban hanh » ban hang
su sach » so sach, vu sach
va than » va thanh, van than, va phan
duc ban » duc tan, duc van, dua ban
hieu va » lieu va, hieu qua
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: su sach tham nang ((x hoi) or (xa hoi)). hieu va than duc ban hanh lai ((cua viet) OR (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tham nang ((x hoi) OR (xa hoi)). hieu va than duc ban hanh lai ((cua viet) OR (hoa viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tham nang ((x hoi) or (xa hoi)). hieu va than duc ban hanh lai ((cua viet) OR (hoa viet))".
• Adding a wildcard symbol may retrieve word variants: su sach tham nang ((x hoi) or (xa hoi)). hieu va than duc ban hanh lai ((cua viet) OR (hoa viet))*.