5IEC 60947-1: 2004 Low-voltage swithchgear and con- trolgear; Part 1: General rules [S]. 275-285.
6ISO 4969-1980 Steel; Macroscopic examination by etching with strong mineral acids I-S].
7ISO 2639- 2003 Determination and verification of the depth of carbruized and hardeded cases I-S].
8ISO 898- 2- 2012 Mechanical properties of fasteners made of carbon steel and alloy steel - Part 2: Nuts with specified property classes - Coarse thread and fine pitch thread [S].
9ISO 898-7-1995 Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm [S].
