Robert W. Chen Alan Zame Chien-Tai Lin Hsiu-fen Wu A Random Version of Shepp's Urn Scheme. 149-164 2005 19 SIAM J. Discrete Math. 1 http://dx.doi.org/10.1137/S0895480102418099 db/journals/siamdm/siamdm19.html#ChenZLW05