Ludwig Ahorner. “Fault-Plane Solutions and Source Parameters of the 1992 Roermond, the Netherlands, Mainshock and Its Stronger Aftershocks from Regional Seismic Data”. Netherlands Journal of Geosciences, vol. 73, Jan. 1994, pp. 199-14, https://njgjournal.nl/index.php/njg/article/view/12462.