Stereocard
From Just Solve the File Format Problem
The stereocard (also called stereo card, stereograph card, stereogram, or stereo view) is a pair of photographic prints mounted on card stock and viewed through a stereoscope to produce a three dimensional image. Stereocards were in popular use from the 1880s through the 1930s.
References
- Stereograph Cards, U.S. Library Of Congress
