using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main(string[] args)

    {

        Book book1 = new Book();

        book1.AddPage("one");   

    }

}

​

public class Book

{

    public string Bookname = "a";

    public List<Page> Pages = new List<Page>();

​

    public void AddPage(string pageTitle)

    {

        Pages.Add(new Page(this, pageTitle));

    }

}

​

public class Page

{

    Book book;

    public Page(Book b, string pagetitle)

    {

        book = b;

        Console.WriteLine(pagetitle);

        Console.WriteLine("I'm from book '{0}'.", book.Bookname);

    }

}