Background. The study is devoted to the introduction into scientific circulation of a cataloged collection of historical sources of the Spanish journalist Pilar Bonet, which were formed in the archival fund No. 30 of the Presidential Center of B.N. Yeltsin in 2023. This fund has documents and samizdat journals of informal socio-political movements of Sverdlovsk region during the perestroika era, which provide new data on the struggle of the Ural general democratic opposition with regional organizations of the CPSU at the turn of the 1980s and 1990s, about which Pilar Bonet will write the book “Impossible Russia. Boris Yeltsin, a Provincial in the Kremlin”. However, samizdat and documents of dissident groups are a new type of written historical sources in modern Russian historiography. This raises the question for the researcher about the specifics of criticism of such documents, their place in the study of the Soviet era, including in the context of regional history of the late Soviet era. The purpose of the study is to conduct a source study analysis of the collec-tion of Ural samizdat from the perestroika era and documents of informal socio-political as-sociations collected in the Pilar Bonet document collection. Materials and methods. The so-lution to the tasks set in the work was achieved through the use of a comparative-historical method during the analysis of documents collected by Pilar Bonet and similar documents from the collections of the Documentation Center of Public Organizations of the Sverd-lovsk Region. Results. The study of documents from the archival collection of Pilar Bonet shows that they contain a representative amount of data on the entire life of informal socio-political movements in the Middle Urals during the perestroika era. This socio-political group, which was formed in the first years of perestroika in Sverdlovsk region, meticulous-ly documented its activities in the socio-political struggle with the party organizations of the region. The authors of the documents focused on protest rallies, criticism of the Soviet system and party organizations, and the publication of information materials on the pro-gress of trials of supporters of informal groupsThese documents are particularly good at showing the activities of such associations as the general democratic movement “Miting-87” and the nationalist movement “Otechestvo”. Conclusions. The study of the collection of documents proves that Pilar Bonet managed to collect a complete and representative col-lection of samizdat magazines and documents through her own initiative. The collection of documents Pilar Bonet collected during her work in Sverdlovsk in 1989–1993 is a unique example of rare historical sources on the topic of the modern history of Russia by a citizen of a foreign state. The introduction of this collection into scientific circulation contributes to a comprehensive study of the socio-political history of the Urals in the era of perestroika.