Techreport (elahmad2011robustness)
El Ahmad, A. S.; Yan, J. & Tayara, M.
The Robustness of Google CAPTCHAs
School of Computer Science, Newcastle University, UK, 2011

Article (melnik2010dremel)
Melnik, S.; Gubarev, A.; Long, J. J.; Romer, G.; Shivakumar, S.; Tolton, M. & Vassilakis, T.
Dremel: interactive analysis of web-scale datasets
Proceedings of the VLDB Endowment, VLDB Endowment, 2010, 3, 330-339