We wish to thank Eckehard Olbrich, Marcus Richter, and Andreas Schmitz who have made contributions to the TISEAN project, and the users who patiently coped with early versions of the software, in particular Ulrich Hermes. We thank Leci Flepp, Nick Tufillaro, Riccardo Meucci, and Marco Ciofini for letting us use their time series data. This work was supported by the SFB 237 of the Deutsche Forschungsgemeinschaft.