Rohit Chadha Luís Cruz-Filipe Paulo Mateus Amílcar Sernadas Reasoning about probabilistic sequential programs. 142-165 2007 379 Theor. Comput. Sci. 1-2 http://dx.doi.org/10.1016/j.tcs.2007.02.040 db/journals/tcs/tcs379.html#ChadhaCMS07