Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, nam thu, nam tu
hanh dai » hanh tai, hanh dao, vanh dai
va triet » va thiet, va trien, ve triet
su sach » so sach, vu sach
sach va » sach xa, sach ha, sach dao
va nang » van nang, da nang, cam nang
cao hoi » cau hoi, cao hoc, tao hoi
va hanh » van hanh, va thanh, va danh
co hoi » co hoc, co loi
dai va » mai va

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 va nang ((cao hoi) OR (co hoi)). hieu van ((am thuc) or (nam thuc)) va hanh dai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach va nang ((cao hoi) OR (co hoi)). hieu van ((am thuc) OR (nam thuc)) va hanh dai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach va nang ((cao hoi) OR (co hoi)). hieu van ((am thuc) or (nam thuc)) va hanh dai va triet".
• Adding a wildcard symbol may retrieve word variants: su sach va nang ((cao hoi) OR (co hoi)). hieu van ((am thuc) or (nam thuc)) va hanh dai va triet*.