Perhaps you should try some spelling variations:
cua triet » cua viet, va triet
cuon sach » duong sach, cuoc cach, co sach
hieu van » hieu va, thien van, lieu va
cac thoi » cac toi, cac hop, cac tro
hanh dai » hanh tai, hanh dao, vanh dai
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
van cac » van hac, van cau, van bac
thoi va » hoi va, thai va, tho va
va hanh » van hanh, va thanh, va danh

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