It sometimes happens in the data-collection process that some links expire, are replaced by others etc.
This is why sometimes you will find a link leading to a “blank” website. In order to make sure this doesn’t prevent access to data, “alternative links” were added. So if a link leads to a blank website, press the “Alternative link”.
Rarely, the “Alternative link” will also lead to a blank website. This would happen, for example due to copyright issues or data retention period expiration.