@article{bwmeta1.element.desklight-082fe791-c00d-478d-87e1-6aaf90511096,
author = {J. Kisy\'nski},
title = {On operator-valued solutions of d'Alembert's functional equation, I},
journal = {Colloquium Mathematicae},
volume = {24},
year = {1971},
pages = {107-114},
zbl = {0239.39004},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.desklight-082fe791-c00d-478d-87e1-6aaf90511096}
}
J. Kisyński. On operator-valued solutions of d'Alembert's functional equation, I. Colloquium Mathematicae, Tome 24 (1971) pp. 107-114. http://gdmltest.u-ga.fr/item/bwmeta1.element.desklight-082fe791-c00d-478d-87e1-6aaf90511096/