Féach ar an rann thíos agus ansin freagair an cheist ina dhiaidh sin sa teanga chéanna leis an rann:  Passage: N. Marwan, M. Romano, M. Thiel and J. Kurths, "Recurrence Plots for the Analysis of Complex Systems", Phys. Rep. 438, 240-329 (2007)  Ceist: Is iad Marwan, Romano, Kurths agus cé iad na húdair?
Thiel