Bigelow, Charles. Chapter 28, Digital Typography, 560. o.. DOI: 10.1038/scientificamerican0883-106 (1983) „All of the methods described in these books are in the public domain; thus anybody can freely use any of the ideas. The only thing I'm retaining control of is the names, TeX and METAFONT(...) If any changes are made, I won't complain, as long as the changed systems are not called TEX or METAFONT.”
CSTUG, Charles University, Prague, March 1996, Questions and Answers with Prof. Donald E. Knuth, reproduced in TUGboat 17 (4) (1996), 355–67. Citation is from page 361. Available online at http://www.tug.org/TUGboat/Articles/tb17-4/tb53knuc.pdf
Bigelow, Charles. Chapter 28, Digital Typography, 560. o.. DOI: 10.1038/scientificamerican0883-106 (1983) „All of the methods described in these books are in the public domain; thus anybody can freely use any of the ideas. The only thing I'm retaining control of is the names, TeX and METAFONT(...) If any changes are made, I won't complain, as long as the changed systems are not called TEX or METAFONT.”