Klein–Gordon oscillator in Kaluza–Klein theory Josevi Carvalho, Alexandre M. de M. Carvalho, Everton Cavalcante and Claudio Furtado Eur. Phys. J. C, 76 7 (2016) 365 Published online: 01 July 2016 DOI: 10.1140/epjc/s10052-016-4189-3