Column strength of tubes elastically restrained against rotation at the ends
A 1938 NASA technical report on the column strength of tubes whose ends are elastically restrained against rotation, prepared for aeronautical engineers and structural researchers. Its pictures are plain engineering graphs on white paper: two line charts plotting average stress against ratio of length to radius, with dotted data points, labelled curves, and a formula beneath, which a designer could draw on for clean technical chart styling and grid layouts.
