Joshua J. Arulanandham, Cristian Calude, Michael J. Dinneen. Balance Machines: Computing = Balancing. In Natasa Jonoska, Gheorghe Paun, Grzegorz Rozenberg, editors, Aspects of Molecular Computing, Essays Dedicated to Tom Head on the Occasion of His 70th Birthday. Volume 2950 of Lecture Notes in Computer Science, pages 36-48, Springer, 2004. [doi]