Editing Functional equation (section)

==References==
*[[János Aczél (mathematician)|János Aczél]], ''[https://books.google.com/books?id=JEB0BFvRwrcC Lectures on Functional Equations and Their Applications]'', [[Academic Press]], 1966, reprinted by Dover Publications, {{ISBN|0486445232}}.
*János Aczél & J. Dhombres, ''[https://books.google.com/books?id=8EWnEh18rVgC&q=%22Functional+Equations+in+Several+Variables%22 Functional Equations in Several Variables]'', [[Cambridge University Press]], 1989.
*C. Efthimiou, ''Introduction to Functional Equations'', AMS, 2011, {{isbn|978-0-8218-5314-6}} ; [https://web.archive.org/web/20230603025341/http://www.msri.org/people/staff/levy/files/MCL/Efthimiou/100914book.pdf online].
*Pl. Kannappan, ''[https://books.google.com/books?id=SdZoCM2OeuIC&dq=%22Functional+Equations+and+Inequalities+with+Applications%22&pg=PA1 Functional Equations and Inequalities with Applications]'', Springer, 2009.
*[[Marek Kuczma]], ''[https://books.google.com/books?id=tFTFBAAAQBAJ&q=%22Introduction+to+the+Theory+of+Functional+Equations+and+Inequalities%22 Introduction to the Theory of Functional Equations and Inequalities]'', second edition, Birkhäuser, 2009.
*Henrik Stetkær, ''[https://books.google.com/books?id=JzS7CgAAQBAJ&dq=%22Functional+Equations+on+Groups%22&pg=PR5 Functional Equations on Groups]'', first edition, World Scientific Publishing, 2013.
*{{cite book|author=Christopher G. Small|title=Functional Equations and How to Solve Them|url=https://books.google.com/books?id=2D2RYbb22nMC|date=3 April 2007|publisher=Springer Science & Business Media|isbn=978-0-387-48901-8}}