A woman was stabbed in Sudbury during a robbery.  The victim was walking with a man when they were approached by another couple.  The second man produced a knife and his female companion grabbed the other woman’s purse.  There was a struggle and the woman was stabbed.  Her friend went after the pair not realizing at first she was hurt.  The woman had to be treated for an injury to her left side and police are looking for the robbers.