ENCollections of manuscripts in Vilnius are stored in three archives: the Lithuanian State Historical Archives, the Central State Archives of Lithuania, and the Lithuanian Literature and Art Archive. They are also stored in the Manuscript Sections of the most important Vilnius libraries: the Library of the Vilnius University, the Wroblewski Library of the Lithuanian Academy of Sciences, and the Lithuanian National Library of Martynas Mažydas. Among the collections are many documents and written texts (referred to by the Latinate word polonica) from different epochs. Polonica texts by Polish writers and poets of the 19th and 20th centuries have been examined mainly by Polish researchers. Vilnius collections consist of many documents presenting the characters of minorum gentium writers such as Czesław Jankowski, Nikodem Erazm Iwanowski, and Maria Rodziewiczówna. Manuscripts are a valuable source of information about these authors. Irena Fedorowicz’s aim in this article is to show the output of archival studies concerning the life and work of 19th- and 20th-century writers. Some of the results have already been published in Lithuanian scholarly publications in the years 2016–2022. Keywords: Vilnius manuscripts, epistolography collections, Czesław Jankowski, Nikodem Erazm Iwanowski, Maria Rodziewiczówna, 19th and 20th century. [From the publication]