Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
phan duc » pham duc, phan tu, phan dau
van hanh » van thanh, ban hanh, van anh
chieu ke » hieu ky, hieu ve, hieu kem
hieu ke » hieu kem, hieu ky, hieu ve
sach ty » sach y, sach tu, sach thu
duc van » duc va, duc tan, duc manh
ty nang » ky nang, ty xang, ty hang
tu sach » thu sach, su sach, te sach
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty nang x hoi. ((hieu ke) or (chieu ke)) phan duc van hanh (kem or kiem) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang x hoi. ((hieu ke) OR (chieu ke)) phan duc van hanh (kem OR kiem) su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang x hoi. ((hieu ke) or (chieu ke)) phan duc van hanh (kem or kiem) su triet*.