Tessman, Thant, 1995. Adding generic functions to Scheme. In SIGPLAN Not., Association for Computing Machinery, New York, NY, USA, vol. 30, pp. 45–50.
Abstract: A generic function is a set of methods, all of which have equivalent semantics but each of which apply to different domains. This document describes how to augment the Scheme programming language with the capability to define multi-method generic functions. Also described are optimization issues and areas of potentially fruitful future exploration.
Moreover, the Chicken Scheme fast-generic egg is based on that.