Perhaps you should try some spelling variations:
thanh hoa » thanh pho
nam thuc » nam thuoc, am thuc, nam tu
nhanh ha » thanh hai, khanh hoa, nhan va
su triet » su viet, su tien, ve triet
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
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: so sach ky nang cao hoi. hieu ve ((nam thuc) OR (nam thu)) ban ((nhanh ha) or (thanh hoa)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang cao hoi. hieu ve ((nam thuc) OR (nam thu)) ban ((nhanh ha) OR (thanh hoa)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang cao hoi. hieu ve ((nam thuc) OR (nam thu)) ban ((nhanh ha) or (thanh hoa)) su triet".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang cao hoi. hieu ve ((nam thuc) OR (nam thu)) ban ((nhanh ha) or (thanh hoa)) su triet*.