أرسل هذا في رسالة قصيرة: Essays on heterogeneous large panel data models

           _    _     _____    _    _    _    _   
    ___   | || | ||  /  ___|| | || | || | |  | || 
   /   || | || | || | // __   | || | || | |/\| || 
  | [] || | \\_/ || | \\_\ || | \\_/ || |  /\  || 
   \__ ||  \____//   \____//   \____//  |_// \_|| 
    -|_||   `---`     `---`     `---`   `-`   `-` 
     `-`