Translation from Bulgarian. Published in the State Gazette (SG) No. 60 of 05.08.1988, amended in SG No. 93 of 02.11.1993, amended in SG No.59 of26.05.1998, amended in SG No. 38 of 17.04.2001, amended in SG No. 46 of 29.04.2002, amended in SG No. 59 of 20.07.2007, in effect from 01.03.2008