Older Potez XV A2 reconnaissance aircraft, used as trainers, including 428 / A3, 449 / A4, 451 /E1 and 447 / E4. Photo dated 1935 which would just be possible both for the Potez XVs and the Junkers F13s in the background. Cropped photo; the wingtip in the foreground is of 435 / A1. We are grateful for any information about the prewar Polish serial numbers and unit code systems. Photo from: Narodowe Archiwum Cyfrowe