Carlos Javier Hernández Castro, Arturo Ribagorda. Remotely Telling Humans and Computers Apart: An Unsolved Problem. In Jan Camenisch, Dogan Kesdogan, editors, iNetSec 2009 - Open Research Problems in Network Security - IFIP WG 11.4 International Workshop, Zurich, Switzerland, April 23-24, 2009, Revised Selected Papers. Volume 309 of IFIP Advances in Information and Communication Technology, pages 9-26, Springer, 2009. [doi]
Abstract is missing.