New Battery for Dell Latitude E6520

Hello,  since my Dell Latitude E6520 battery is now completely wide, I am looking for a replacement. Although Google spits out several things really seriously not seem to me to some pages but.  http://www.pc-akkus.com/dell-latitude-e6520.html although such does not look wrong, but a missing address in the imprint somehow seems daunting. Therefore, the question if anyone has experience with relevant online stores. Please no e-Bay dealer account is not available on my part ;) Thanks in advance :)