At Drupal.hu, we host a list of Hungarian Drupal sites, into which submission is open. But publishing is moderated, partly because screenshots should be taken somehow, and we often get false submissions. The Visegrad.info Internet Magazine seemed to be a false positive too, it's footer saying that it runs on 3N CMS. But looking at the source code, obvious snippets like @import "/misc/drupal.css"; showed that 3N CMS is actually Drupal. So I was on to see, what company developed this wonderful product.
Well, 3N.cz is that company, and their own site runs on Drupal, although seemingly they tried to mask drupal.css renaming it to main.css. Snippets like <div class="block-i18n" id="block-i18n-0"> easily show Drupal. So they have a few solutions like a CMS (named 3N CMS), a CRM and an eCommerce (seemingly named 3N eShop) product. By looking at the company reference sites, out of the 5 sites listed, the three recent ones run on Drupal.
It is surprising to see that they don't see the business sense in advertising themselfs as a Drupal shop, and instead opt to market their solutions as their own creations, basically looking like a closed company. Maybe they think they get better amount of money, or their clients will not choose another Drupal shop if they are not satisfied. Unfortunate.