Kewenangan Kepala Daerah Dalam Pengelolaan Badan Usaha Milik Daerah (Studi Kasus Keberlakuan Surat Bupati Bojonegoro No. 050/872/412/12/2005) = The Authority of Regional Heads in Managing Regional Owned Enterprises (Case Study of the Enforceability of the Letter of Bojonegoro Regent No 050/872/412/12/2005)