Shannon's basic theorem on the capacity of a channel is generalized to the case of a class of memoryless channels. A generalized capacity is defined and is shown to be the supremum of attainable transmission rates when the coding and decoding procedure must be satisfactory for every channel in the class.
"The Capacity of a Class of Channels." Ann. Math. Statist. 30 (4) 1229 - 1241, December, 1959. https://doi.org/10.1214/aoms/1177706106