<article>
    <h2>{!! $product->slug !!}</h2>

    internal
    {!! $product->getValue('internal_article_number') !!}
    {!! $product->getValue('internal_article_number') !!}
    {!! $product->attributes->get('internal_article_number') !!}
    <pre>{!! print_r($product->toArray()) !!}</pre>
</article>