Author not established. [nr. Date not established. EHREA archive: /library/documents/doc-3f00447b6f0c14c87452fdcb/
[1] [nr. Original source: http://www.ehrea.org/erit136.pdf. Preserved original: /library/originals/499962f14832f89527dac8eaaa7dc2059a79ae37ca04f811b67f7a73e15f34e6.pdf. SHA-256: 499962f14832f89527dac8eaaa7dc2059a79ae37ca04f811b67f7a73e15f34e6