%0 Journal Article %A McDonald, David R. %T On Upcrossing Probabilities %J Canadian journal of mathematics %D 1977 %P 806-818 %V 29 %N 4 %U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-083-0/ %R 10.4153/CJM-1977-083-0 %F 10_4153_CJM_1977_083_0