Coba jelasin Penelitian dari Kartu Octopus dong

An Arms Length Evaluation of Octopus . By John Paynter and Patrick Law, University of Auckland working paper.

Working paper. Octopus and Mondex - the Social Shaping of Money . Lucia Siu, University of Edinburgh working paper. April 2002.

The Octopus System - The Hong Kong Mass Transit System . World Bank presentation from MTR. Retrieved 1 February 2004.

Hong Kong Smart Card System . World Bank presentation. Retrieved 1 February 2004.