AdamyanV. M.; ArovD. Z.; BerezanskyY. M.; GorbachukV. I.; GorbachukM. L.; MikhailetsV. A.; SamoilenkoA. M. Mark Grigorievich Krein (to the centenary of his birth). Ukrains’kyi Matematychnyi Zhurnal, v. 59, n. 5, p. 579-587, 25 May 2007.