Norman Poh Josef Kittler Ray Smith J. Rafael Tena A Method for Estimating Authentication Performance over Time, with Applications to Face Biometrics. 360-369 2007 conf/ciarp/2007 CIARP http://dx.doi.org/10.1007/978-3-540-76725-1_38 db/conf/ciarp/ciarp2007.html#PohKST07