https://www.kommersant.ru/doc/4740949
https://novayagazeta.ru/articles/2021/03/21/stariki-shpiony
https://www.radiosvoboda.org/a/news-bolgaria-rosia-shpyhunstvo/31162088.html
https://www.gazeta.ru/politics/2021/03/20_a_13518728.shtml
https://www.inopressa.ru/article/10Mar2021/bild/rtde.html
https://nvo.ng.ru/history/2021-03-04/1_1131_history1.html
https://www.znak.com/2021-03-01/raspad_gosudarstva_v_rossiyskoy_stolice_ubiystv_reportazh
https://www.inopressa.ru/article/26Feb2021/spiegel/spionage.html