APA (7th ed.) Citation

Inter Nationes, B., & Brüder Hartmann, B. (1986). Photographic Masterpieces. No. 1 "Cologne in Winter". about 1920.

Chicago Style (17th ed.) Citation

Inter Nationes, Bonn, and Berlin Brüder Hartmann. Photographic Masterpieces. No. 1 "Cologne in Winter". About 1920. 1986.

MLA (8th ed.) Citation

Inter Nationes, Bonn, and Berlin Brüder Hartmann. Photographic Masterpieces. No. 1 "Cologne in Winter". About 1920. 1986.

Warning: These citations may not always be 100% accurate.