Hellgardt, Alexander Business and Tax Law, MPI for Tax Law and Public Finance, Max Planck Society;
http://www.mpg.de/4673878/Regulierung_Privatrecht (全文テキスト(全般))
Hellgardt, A. (2012). Regulierung mittels Privatrecht / Regulation by means of private law. Jahrbuch / Max-Planck-Gesellschaft, 2012.