@article{TM_2002_237_a18,
     author = {A. N. Shiryaev and E. Valkeila and L. Yu. Vostrikova},
     title = {On {Lower} and {Upper} {Functions} for {Square} {Integrable} {Martingales}},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {290--301},
     publisher = {mathdoc},
     volume = {237},
     year = {2002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TM_2002_237_a18/}
}