@article{10_4064_ba53_4_9,
     author = {Adam Os\k{e}kowski},
     title = {Two {Inequalities} for the {First} {Moments} of {a
Martingale,} its {Square} {Function
} and its {Maximal} {Function}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {441--449},
     publisher = {mathdoc},
     volume = {53},
     number = {4},
     year = {2005},
     doi = {10.4064/ba53-4-9},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba53-4-9/}
}