Depending on the context of the articles you are looking for, "PES" typically refers to one of the following: What are PES? A review of definitions and an extension
The phrase appears to be a misencoded version of the Russian phrase "Статьи на тему: 'pes'" , which translates to "Articles on the topic: 'pes'" . This specific wording is frequently found as a heading on Russian-language websites, blogs, or forums. Статьи РЅР° тему: "pes"