Jochen Braunmiller, Torsten Dahm, and Klaus-Peter Bonjer. “Source Mechanism of the 1992 Roermond, the Netherlands, Earthquake from Inversion of Regional Surface Waves (extended Abstract)”. Netherlands Journal of Geosciences, vol. 73, Jan. 1994, pp. 225-7, https://njgjournal.nl/index.php/njg/article/view/12464.