ウルム市電
Neil Pulling (2020-9). “Systems Factfile No.155 Ulm, Germany”. Tramways & Urban Transit No.993 (LRTA) 83: 351-355. http://www.bowe.cc/techlib/pdf/Tramways_and_Urban_Transit_vol83_no993_1598341243.pdf 2021年5月7日閲覧。.