(Mobiles) Bezahlen aus der Sicht des Online-Händlers: Status Quo und Perspektiven. - Jens-Werner Hinrichs; Karsten Stroborn; Sebastian van Baal (Workshop Mobile Commerce, 2004)

Not all seals are equal: An experimental investigation of the effect of third-party seals on purchase probability in electronic commerce. - Sebastian van Baal (Electron. Commer. Res., 2015)