@article{ZNSL_2023_527_a0,
     author = {V. I. Vasyunin and P. B. Zatitskii},
     title = {Some extremal problems for martingale transforms. {I}},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {5--53},
     publisher = {mathdoc},
     volume = {527},
     year = {2023},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2023_527_a0/}
}