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Photomicrograph 500x, faded 3M print, cross section. Credit: Karsta Knaack.
- Photomicrograph 500x, faded 3M print, cross section. Credit: Karsta Knaack.
- Faded 3M positive. Credit: Carsta Knaack, HTW Berlin.
- Faded 3M positive. Credit: Carsta Knaack, HTW Berlin.