1. A little adjustment…;Chapdelaine,1990
2. Forced opening and positive action limit switches, used for guards,1989
3. Safety of machinery - Basic concepts, general principles for design - Part 2: Technical principles and specifications,1991
4. Safety of machinery interlocking devices with and without guard locking - General principles and specifications for design,1990
5. Code of practice. Safeguarding of machinery,1988