Analysis of information sources in references of the Wikipedia article "Proof of concept" in English language version.
January 25, 26, and February 27, 1967, review of adequacy of policy planning for aeronautical research and development and of what Congress, Executive Branch of government, and private industry can do to insure that national aeronautical goals are met
proof of concept[:] Evidence that demonstrates that a business model or idea is feasible.
December, 1, 2, 4, 8–11, 1969,
