That's papers that are citing them. The reason for no links is explained on the page,

> The distribution rules for published papers vary by the publication in which the paper appears. Due to these rules, a public web-source of each paper may not be immediately available. If full version is not linked below or available elsewhere on the Internet (Google Scholar can be helpful for this), most, if not all of these publications are freely available at a local municipal or collegial library. These articles are written for scientists, so the contents are fairly technical.