1. BILSTEIN, J. / DAMM, W. Top-down tree-transducers for infinite trees I, Proc. 6 ième colloque sur les Arbres en Algébre et en Programmation, Lecture Notes in Computer Science (1981), to appear
2. DAMM, W. An algebraic extension of the Chomsky-Hierarchy, Proc. conf. on Mathematical Foundations of Computer Science, Lecture Notes in Computer Science 74 (1979), 266–276, Springer Verlag
3. DAMM, W. The IO-and OI-hierarchies, Schriften zur Informatik und Angewandten Mathematik 41 (1980), RWTH Aachen, submitted for publication
4. DAMM, W. Top-down tree-transducers for infinite trees, in preparation
5. DAMM, W. / GOERDT,A. Level-n PDA's, in preparation