Androulakis, Emmanouil, Christos Koukouvinos, and Filia Vonta. 2012. “ON THE UNIFORM FRAILTY MODEL WITH PENALIZED LIKELIHOOD AND CLUSTERED DATA”. Journal of Reliability and Statistical Studies 5 (January):97-106. https://journals.riverpublishers.com/index.php/JRSS/article/view/21961.