Editing Modus ponens (section)

== Sources ==
*Herbert B. Enderton, 2001, ''A Mathematical Introduction to Logic Second Edition'', Harcourt Academic Press, Burlington MA, {{ISBN|978-0-12-238452-3}}.
* Audun Jøsang, 2016, ''Subjective Logic; A formalism for Reasoning Under Uncertainty'' Springer, Cham, {{ISBN|978-3-319-42337-1}}
*[[Alfred North Whitehead]] and [[Bertrand Russell]] 1927 ''Principia Mathematica to *56 (Second Edition)'' paperback edition 1962, Cambridge at the University Press, London UK. No ISBN, no LCCCN.
*[[Alfred Tarski]] 1946 ''Introduction to Logic and to the Methodology of the Deductive Sciences'' 2nd Edition, reprinted by Dover Publications, Mineola NY. {{ISBN|0-486-28462-X}} (pbk).