On p-Sidon Sets G. JohnsonGordon Woodward Indiana University Mathematics Journal 1975 text pdf 10.1512/iumj.1975.24.24013 10.1512/iumj.1975.24.24013 en Indiana Univ. Math. J. 24 (1975) 161 - 167 state-of-the-art mathematics http://iumj.org/access/