@misc{JSFU_2021_14_6_a0,
     title = {Preface by the editor of the issue},
     journal = {\v{Z}urnal Sibirskogo federalʹnogo universiteta. Matematika i fizika},
     pages = {677--678},
     publisher = {mathdoc},
     volume = {14},
     number = {6},
     year = {2021},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JSFU_2021_14_6_a0/}
}