1. Italian Ministerial Decree (D.M. of 15/1/1969);Gazzetta Ufficiale No. 16,1969
2. Italian Legislative Decree No. 118 (D.L. of 27/1/1992);Supplement of Gazzetta Ufficiale No. 40,1992
3. E C Directive 81/602, Publications of the European Communities;Document No. L 222 32-33,1981