Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
va hanh » va thanh, va danh, ban hanh
cai hoi » dai hoi, cai hoa, lai hoi
lai cua » dai cua, hai cua, lai chau
hieu ke » hieu kem, chieu ke, hieu ky
sach ky » sac ky, sach y, sach ty
cau tuc » cau truc, cau tu, cau luc
ke cau » ket cau
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang ((cai hoi) or (cau hoi)). hieu ke cau tuc ((va hanh) OR (van hanh)) lai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang ((cai hoi) OR (cau hoi)). hieu ke cau tuc ((va hanh) OR (van hanh)) lai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang ((cai hoi) or (cau hoi)). hieu ke cau tuc ((va hanh) OR (van hanh)) lai cua te".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ((cai hoi) or (cau hoi)). hieu ke cau tuc ((va hanh) OR (van hanh)) lai cua te*.