Photographs of important revolutionaries were inserted in albums for use as reference and instructional and recognition materials. One large album, with each mounted photograph given a reference number, was used as the basic reference in the Paris Okhrana Office. The collection contains fourteen medium-size albums in approximately the same arrangement, some of them with names under the pictures, some with an index of names attached to the covers. Another set of fifteen pocket-size albums in a similar order was entrusted to agents assigned to surveillance tasks in the field. Not all of these albums are in the same arrangement of pictures, while the numbering system for persons in the illustrations is usually the same. Thus, the agent reporting from the field did not have to mention the name of his target, but only the number assigned in the album.