“…Such as the sources of formal law, namely the forms of self-appearance of legal norms, as well as the content of the legal norms themselves (sources of material law). The modern legal order recognizes legal norms such as: (i) legislation (ii) jurisprudence (iii) doctrine (iv) Conventions (Soedjono, 2005) Today's legal norms are often and often only understandable through the history of the law. For example Henri de Page in the book "Traite Eleentaire de Droit Civil" 1930-1950.…”