Maintenance work on the ZORA databases is scheduled for Wednesday 22 May 2019 from 20:00-22:00. During this period ZORA and JDB will not be available. Thank you for your understanding.
Black, D V; Gopi, M; Kuester, F; Wessel, F; Pajarola, R (2007). Visualizing flat spacetime: viewing optical versus special relativistic effects. American Journal of Physics, 75(6):540-545.