TeXbook e Metafontbook si possono scaricare in formato dvi da qui:
http://www.math.uni-hamburg.de/home/ammann/tex/tetex/doc/#knuth
Che si possano scaricare non significa necessariamente che sia legale procurarseli in quel modo. Riporto per conoscenza le prime righe del sorgente del METAFONTBook:
% This manual is copyright (C) 1986 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 METAFONTbook.
% Permission for any other use of this file must be obtained in writing
% from the copyright holder and also from the publisher (Addison-Wesley).
Inoltre, stampandoseli ci si perdono le gustone illustrazioni all’inizio dei capitoli 😉