6.1	NASA-STD-5020, December 2, 2012	Requirements for Threaded Fastening systems in Spaceflight Hardware
6.2	DIN 4768:1990	Determination of values of surface roughness parameters RA, RZ, RMAX using Electrical Contact (Stylus) Instruments Concepts and Measuring Conditions.
6.3	J.H. Bickford	An Introduction to the Design and Behaviour of Bolted Joints, Marcel Dekker, 1981.
6.4	FISHER. J, STRUIK. J.H.A.	Guide to Design Criteria for Bolted and Riveted Joints, John Wiley & Sons, 1974.