public function getParent ($category, $depth = 1)
		{
			if ($category instanceof $this->_modelClass and $depth > 0)
			{
				if ($category->depth == $depth)
					return $category;
				foreach ($this->_data as $item)
					if ($category->lft > $item->lft and $category->rgt < $item->rgt and $item->depth == $depth)
						return $item;
			}

			return null;
		}