public function getHyperlink($pCellCoordinate)
    {
        // return hyperlink if we already have one
        if (isset($this->hyperlinkCollection[$pCellCoordinate])) {
            return $this->hyperlinkCollection[$pCellCoordinate];
        }

        // else create hyperlink
        $this->hyperlinkCollection[$pCellCoordinate] = new Hyperlink();

        return $this->hyperlinkCollection[$pCellCoordinate];
    }