CorPatch® – A smartphone-based BLS guidance and feedback system: Improvements in laypersons' chest compressions. (September 2017) - Birkmaier, Stephan; Helmert, Jens R.; Böttiger, Bernd W.; Castren, Maaret; Roth, Matthias; Schorling, Per; Pannasch, Sebastian; Müller, Michael; Heller, Axel