Perhaps you should try some spelling variations:
thieu nang » thien nang, thieu khang, thieu quang
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
tham duc » pham duc, tham du, than duc
tan hanh » tan thanh, tang hanh, toan hanh
hanh lai » hanh lam, hanh tai, thanh lap
ve triet » va trien, su triet
su sach » so sach, vu sach
co hoi » co hoc, co loi
lai ve » loai ve, lai va, la ve
x hoi » xa hoi, x ho, 5 hoi
o hoi » o hoc, o hai, o hoa

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 thieu nang ((((x hoi) OR (o hoi))) or (co hoi)). hieu van tham duc tan hanh lai ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thieu nang ((((x hoi) OR (o hoi))) OR (co hoi)). hieu van tham duc tan hanh lai ve triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thieu nang ((((x hoi) OR (o hoi))) or (co hoi)). hieu van tham duc tan hanh lai ve triet*".