<hi xmlns="http://www.tei-c.org/ns/1.0" rend="bold">Adobe Systems</hi> (2006): <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">PDF Reference, Sixth Edition: Adobe Portable Document Format Version 1.7</hi><ref xmlns="http://www.tei-c.org/ns/1.0" target="http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_1-7.pdf">http://wwwimages.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_1-7.pdf</ref> [letzter Zugriff 25. August 2016].