The Linearized Equations of Water Waves Brian Lau Indiana University Mathematics Journal 1973 text pdf 10.1512/iumj.1973.22.22020 10.1512/iumj.1973.22.22020 en Indiana Univ. Math. J. 22 (1973) 233 - 266 state-of-the-art mathematics http://iumj.org/access/