public override string ToString()
 {
     if (Person != null)
     {
         return(Person.ToString());
     }
     else if (ForeignCitizen != null)
     {
         return(ForeignCitizen.ToString());
     }
     else
     {
         return(string.Empty);
     }
 }
 public bool Equals(ElectronicStatementAuthor author)
 {
     if (Person != null && author != null)
     {
         return(Person.Equals(author.Person));
     }
     else if (ForeignCitizen != null && author != null && author.ForeignCitizen != null)
     {
         return(ForeignCitizen.Equals(author.ForeignCitizen));
     }
     else
     {
         return(false);
     }
 }