@article{10_4153_CMB_2016_084_8,
     author = {Jensen, Gerd and Pommerenke, Christian},
     title = {On the {Structure} of the {Schild} {Group} in {Relativity} {Theory}},
     journal = {Canadian mathematical bulletin},
     pages = {774--790},
     year = {2017},
     volume = {60},
     number = {4},
     doi = {10.4153/CMB-2016-084-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2016-084-8/}
}