April 1934
The probability law for the sum of $n$ independent variables, each subject to the law $\left( {{1 \mathord{\left/ {\vphantom {1 {\left( {2h} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)\operatorname{sech} \left( {{{\pi x} \mathord{\left/ {\vphantom {{\pi x} {\left( {2h} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)$
W. D. Baten
