Texty na webu:
Ravi Boppana a Mike Sipser, The complexity of finite functions, in: Handbook of Theoretical Computer Science, Vol.A, ed.J. van Leeuwen, (1990), str.757 - 804.
Alexander A. Razborov, Stephen Rudich, Natural proofs, in: Proc. of the 26th Annual ACM Symposium on the Theory of Computing, (1994), 204-213.
Ingo Wegener, The complexity of Boolean functions, online edition.