GetCapabilities (GET):

http://sg.geodatenzentrum.de/wms_topplus_web_world?REQUEST=GetCapabilities&VERSION=1.3.0&SERVICE=wms

GetMap (GET):

http://sg.geodatenzentrum.de/wms_topplus_web_world?VERSION=1.3.0&REQUEST=GetMap&CRS=CRS:84&BBOX=12.146967276104759,51.129075264840068,12.637377886630142,51.540429426193072&WIDTH=1129&HEIGHT=947&LAYERS=web&STYLES=&FORMAT=image/png