@article{MAN_1989__284_4_164556,
     author = {Peter Imkeller},
     title = {On inequalities for two-parameter martingales.},
     journal = {Mathematische Annalen},
     pages = {329--342},
     publisher = {mathdoc},
     volume = {284},
     number = {4},
     year = {1989},
     zbl = {0648.60052},
     url = {http://geodesic.mathdoc.fr/item/MAN_1989__284_4_164556/}
}