@article{polakis:syssec11,<br>
author = {Iasonas Polakis and Georgios Kontaxis and Sotiris Ioannidis},<br>
title = {CAPTCHuring Automated (Smart) Phone Attacks},<br>
journal ={SysSec Workshop},<br>
volume = {0},<br>
isbn = {978-0-7695-4530-1},<br>
year = {2011},<br>
pages = {27-34}, <br>
publisher = {IEEE Computer Society},<br>
}