From the publisher’s website:

REFERENCES – a new series of A-4 size volumes. Each consists of 16–24 pages and includes selected archive photos, color painting schemes or 3D renders. Some books would contain scale drawings, too. One can find high-quality decal sheets in 1/48th and 1/72nd scales of one specific painting scheme. If the illustration differs in details from the decal, we will present photos which were used to develop sheets. Series for modelers as a supplement to other publications or compilation of already published materials.