Palm, G Former Department Structure and Function of Natural Nerve-Net , Max Planck Institute for Biological Cybernetics, Max Planck Society; Max Planck Institute for Biological Cybernetics, Max Planck Society;
https://link.springer.com/content/pdf/10.1007/BF00344243.pdf (Publisher version)
Palm, G. (1978). On representation and approximation of nonlinear systems. Biological Cybernetics, 31(2), 119-124. doi:10.1007/BF00344243.