[WillAdams]

Except that PDF shouldn't exist since it was generated in flagrant disregard for the copyright/comment:

    % This manual is copyright (C) 1984 by the American Mathematical Society.
    % All rights are reserved!
    % The file is distributed only for people to see its examples of TeX input,
    % not for use in the preparation of books like The TeXbook.
    % Permission for any other use of this file must be obtained in writing
    % from the copyright holder and also from the publisher (Addison-Wesley).
    \loop\iftrue
      \errmessage{This manual is copyrighted and should not be TeXed}\repeat

If you want a free PDF on TeX try _TeX for the Impatient_:

https://tug.ctan.org/info/impatient/book.pdf

If you want a copy of _The TeXbook_, buy it.

[wrs]

I love the subtle humor in misusing “copyright” as a verb and then misusing “TeX” the same way.