Prządka, A., J. Miedzik, K. Gumowski, S. Goujon-Durand, and J.E. Wesfreid. 2008. “The Wake Behind the Sphere; Analysis of Vortices During Transition from Steadiness to Unsteadiness”. Archives of Mechanics 60 (6): 467-74. http://am.ippt.gov.pl/index.php/am/article/view/v60p467.