Ibid. Commentary to Art. 12. § 20, 21. P. 237–238.

OECD Report on Attribution of Profits to Permanent Establishments (2008). § 97. P. 31.

Annual Tax Act implements Authorized OECD Approach into German tax law. URL: http://taxinsights.ey.com/archive/archive-pdfs/Annual-Tax-Act-implements-OECD-Approach-in-German-tax-law-.pdf.