Cosmological horizon entropy and generalized second law for flat Friedmann universe Titus K. Mathew, Aiswarya R and Vidya K. Soman Eur. Phys. J. C, 73 10 (2013) 2619 Published online: 22 October 2013 DOI: 10.1140/epjc/s10052-013-2619-z