protected function _createTree( MW_Tree_Node_Interface $node, MShop_Catalog_Item_Interface $item,
		array $listItemMap, array $refItemMap )
	{
		foreach( $node->getChildren() as $child )
		{
			$listItems = array();
			if ( array_key_exists( $child->getId(), $listItemMap ) ) {
				$listItems = $listItemMap[ $child->getId() ];
			}

			$refItems = array();
			if ( array_key_exists( $child->getId(), $refItemMap ) ) {
				$refItems = $refItemMap[ $child->getId() ];
			}

			$newItem = $this->_createItem( array(), $listItems, $refItems, array(), $child );
			$item->addChild( $newItem );

			$this->_createTree( $child, $newItem, $listItemMap, $refItemMap );
		}
	}