Nerve Axon Equations: 1 Linear Approximations John Evans Indiana University Mathematics Journal 1972 text pdf 10.1512/iumj.1972.21.21071 10.1512/iumj.1972.21.21071 en Indiana Univ. Math. J. 21 (1972) 877 - 885 state-of-the-art mathematics http://iumj.org/access/