I am indebted to Jyri Marviala (Automatia Rahakortit Oy), Françoise Nollet (Banksys), Marc Ronkar (Banque centrale du Luxembourg),
Ronny Klein (CETREL), Rein Kieviet (De Nederlandsche Bank), Christian Stark (Deutsche Bundesbank), Ewald Judt and Robert Komatz
(Europay Austria), Volker Koppe (EURO Kartensysteme), Theresa Lee (Network for Electronic Transfers, Singapore), Joey Wong,
Loretta Wong and Eric Tai (Octopus Cards), and Adrian Eberle (Telekurs) for data, background information and/or comments.