The Secretary of Defense himself has classified them as Class Triple-A Ultra-Hyper Top Secret.
"The Foreign Hand Tie"
Gordon Randall Garrett
With full bibliography, classified list, and index of engravers.
"Fine Books"
Alfred W. Pollard
It was difficult to classify this literature, for the extreme beauty and emotion which pervaded it lifted it above ordinary prose and yet because of the absence of measure it was not classified as poetry.
"The Literature of Ecstasy"
Albert Mordell