@article{ZNSL_2021_501_a4,
     author = {G. Buritic\'a and N. Meyer and T. Mikosch and O. Wintenberger},
     title = {Some variations on the extremal index},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {52--77},
     publisher = {mathdoc},
     volume = {501},
     year = {2021},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2021_501_a4/}
}