Objects and session

Hi, I'm trying to create an object called Folder and in it I want to keep x Paper objects. Is it possible to keep these objects in a session? So I don't have to load the entire folder everytime I want to load view a page in the folder. I just want to load (from the db) when I'm getting a new Folder

My objects look like this:

Folder:
<?php
class Folder
{
    var $papers;            // Paper in the folder
        var $myIndex;
        var $myName;           // Category of the folder e.g Examples
        var $myDescription; //Describe whats in the folder
        var $myImage;            //Standard image of folder
   
     function Folder($name,$description,$image) {
          $this->myIndex      = 0;
          $this->myName     = $name;
          $this->myDescription = $description;
          $this->myImage     = $image;
     }  
   
   
    // Add a paper to the folder
    function addPaper ($paper) {
        $this->papers[$this->myIndex] = $paper;
        $this->myIndex++;
    }
   
    function getPaper ($index) {
         return $this->papers[$index];
    }
   
    function getName() {
         return $this->myName;
    }
   
    function getDescription() {
         return $this->myDescription;
    }
   
    function getImage() {
         return $this->myImage;
    }
   
    function getSize() {
         return $this->myIndex;
    }
}
?>


Paper:
<?php
class Paper
{
     
     var $myId;       // Id number in the database
     var $myFolder;     // Name of the folder it belongs to (e.g. News, Info)
     var     $myTitle;     // The title of the paper
     var     $myContent;     // The actual "article"
     var     $myImage;     // Name of the image associated with the paper
         
     function Paper($id,$folder,$title,$content,$image) {
         
          $this->myId          =     $id;
          $this->myFolder     =     $folder;
          $this->myTitle     =     $title;
          $this->myContent=     $content;
          $this->myImage     =     $image;
     }
         
     function getId() {
          return $this->myId;
     }
     
     function getFolder() {
          return $this->myFolder;
     }
     
     function getTitle() {
          return $this->myTitle;
     }
     
     function getContent() {
          return $this->myContent;
     }
     
     function getImage() {
          return $this->myImage;
     }
}
?>

/Mattias