Check the following citations:
A.Beste, K.Dressler, H.Kotzle, W.Kruger, 1992, Multiaxial Rainflow - A consequent continuation of Professor Tatsuo Endo's work, Butterworth Heinemann Ltd.
Dreßler, K., Carmine, R., Kruger, W.: The multiaxial rainflow method. In: K.T.Rie (ed.) Low cycle fatigue...