A novel noncooperative near-range radar network for traffic guidance and control on airport surfaces. - Karl-Heinz Bethke; Bernd Röde; Martin Schneider; Arno Schroth (IEEE Trans. Control. Syst. Technol., 1993)

An autonomous, non-cooperative, wide-area traffic monitoring system using space-based radar (TRAMRAD). - David Hounam; Stefan Valentin Baumgartner; Karl-Heinz Bethke; Martina Gabele; Erich Kemptner; Dieter Klement; Gerhard Krieger; Gerald Rode; Karl-Hans Wägel (IGARSS, 2005)