La Caricature: Art et Manifeste Du XVI siecle a nos Jours (Skira, Geneva 1974) written by Ronald Searle, Claude Roy and Bernd Bornemann. and John Edwin Jackson.At the beginning of the book Searle writes some authentic reflexions that come across almost as a manifesto on caricature. This can be a starting point for reflexion. I loved reading it and hope you enjoy it as well.