Perhaps you should try some spelling variations:
sach tham » sach nha
tham nang » nham nang, tham lang, tham nhung
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
hanh lai » hanh lam, hanh tai, thanh lap
tan hanh » tan thanh, tang hanh, toan hanh
tham duc » pham duc, than duc, thach duc
tham du » thap du, tham do, pham duc
su sach » so sach, vu sach
lai va » loai va, mai va, dai va
o hoi » co hoi, o hoc, o hai
x hoi » xa 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 (o hoi)). hieu van ((tham duc) OR (tham du)) tan hanh lai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tham nang ((x hoi) OR (o hoi)). hieu van ((tham duc) OR (tham du)) tan hanh lai va triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tham nang ((x hoi) or (o hoi)). hieu van ((tham duc) OR (tham du)) tan hanh lai va triet*".