P-IV bis, 1920 Public domain photograph - aircraft, aviation, free to use, no copyright restrictions image - Picryl description
P-IV, 1921 Public domain photograph - aircraft, aviation, free to use, no copyright restrictions image - Picryl description
P-IV, 1921 Public domain photograph of experimental aircraft, prototype, aviation design and development, no copyright restrictions image - Picryl description
Из фотоархива Василия Васильевича Сапожникова.
Из альбома Льюиса Уотсона, секретаря ХСМЛ (YMСA) в Харбине
Харбин в 1927
