The probability law for the sum of $n$ independent variables, each subject to the law $\left( {{1 \mathord{\left/
{\vphantom {1 {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)\operatorname{sech} \left( {{{\pi x} \mathord{\left/
{\vphantom {{\pi x} {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)$
@article{1183497364,
author = {Baten, W. D.},
title = {The probability law for the sum of $n$ independent variables, each subject to the law $\left( {{1 \mathord{\left/
{\vphantom {1 {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)\operatorname{sech} \left( {{{\pi x} \mathord{\left/
{\vphantom {{\pi x} {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)$},
journal = {Bull. Amer. Math. Soc.},
volume = {40},
number = {12},
year = {1934},
pages = { 284-290},
language = {en},
url = {http://dml.mathdoc.fr/item/1183497364}
}
Baten, W. D. The probability law for the sum of $n$ independent variables, each subject to the law $\left( {{1 \mathord{\left/
{\vphantom {1 {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)\operatorname{sech} \left( {{{\pi x} \mathord{\left/
{\vphantom {{\pi x} {\left( {2h} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {2h} \right)}}} \right)$. Bull. Amer. Math. Soc., Tome 40 (1934) no. 12, pp. 284-290. http://gdmltest.u-ga.fr/item/1183497364/