Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
nam thuc » nam thuoc, nam thu, nam tu
hieu van » hieu va, thien van, lieu va
sach xa » sach dao, sach nha, sach bai
cao hoi » cau hoi, co hoi, cao hoc
sach va » sach ha, sach dao, sach nha
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua

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