Vincenzo Manca. A Recurrent Enumeration of Free Hypermultisets. In Jozef Kelemen, Alica Kelemenová, editors, Computation, Cooperation, and Life - Essays Dedicated to Gheorghe Paun on the Occasion of His 60th Birthday. Volume 6610 of Lecture Notes in Computer Science, pages 16-23, Springer, 2011. [doi]
Abstract is missing.