@incollection{AST_1988__157-158__129_0,
     author = {Dubins, Lester E. and Schwarz, Gideon},
     title = {A sharp inequality for sub-martingales and stopping-times},
     booktitle = {Colloque Paul L\'evy sur les processus stochastiques (22-26 juin 1987. \'Ecole Polytechnique, Palaiseau)},
     series = {Ast\'erisque},
     pages = {129--145},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {157-158},
     year = {1988},
     zbl = {0671.60041},
     language = {en},
     url = {http://www.numdam.org/item/AST_1988__157-158__129_0/}
}