Perhaps you should try some spelling variations:
cuon sach » duong sach, cuoc cach, nuoc sach
su triet » su viet, su tien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
cac thoi » cac toi, cac tro, cac thu
xa hanh » xa thanh, xa khanh, va hanh
co sach » bo sach, hoc sach
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((co sach) or (cuon sach)) ty nang ma hoa. hieu ve ((cac thoi) OR (cac hop)) xa hanh lai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((co sach) OR (cuon sach)) ty nang ma hoa. hieu ve ((cac thoi) OR (cac hop)) xa hanh lai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((co sach) or (cuon sach)) ty nang ma hoa. hieu ve ((cac thoi) OR (cac hop)) xa hanh lai su triet".
• Adding a wildcard symbol may retrieve word variants: ((co sach) or (cuon sach)) ty nang ma hoa. hieu ve ((cac thoi) OR (cac hop)) xa hanh lai su triet*.