@article{ZNSL_2002_284_a4,
     author = {L. Yu. Kolotilina},
     title = {A class of optimally conditioned block $2\times2$ matrices},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {64--76},
     publisher = {mathdoc},
     volume = {284},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2002_284_a4/}
}