The publishing house "RIPOL Classic" presents a series of memoirs "Ad Fontes: secrets and heroes of the Century." The series is edited by historian Anna Esparza. The goal of the series is to present previously unpublished archival materials from families of the Russian emigration of the first wave, accompanying them with documentary information. The conceptual difference between the book series “Ad Fontes: secrets and heroes of the Century” from other book series is that documents of personal origin cover the entire 20th century and belong to representatives of several generations of the same family. The first book of the series is made up of memoirs, diary entries, letters, and stories of representatives four generations of the Koshko family (from the memoirs of the head of the criminal investigation of the Russian Empire, Arkady Frantsevich Koshko, to the diary entries of the French journalist Dmitry de Koshko). These archival materials have not been published before. The book is a unique document of the era, telling “in the first person” about the main events of the 20th century.