Gabriel Bie Ravndal (1938). Stories of the East-vikings. Augsburg publishing house. p. 173. Archived from the original on 17 April 2023. Retrieved 30 January 2023.
"Sveerne". www.fortidensjelling.dk. Archived from the original on 7 May 2021. Retrieved 7 April 2021.
kulichki.net
gumilevica.kulichki.net
Pavel Kokovtsov, when publishing a Russian translation of the letter in 1932, argued that FRS may refer to Thrace, where the Rus' forces were defeated by the armies of Lecapenus (onlineArchived 6 May 2007 at the Wayback Machine).
Gabriel Bie Ravndal (1938). Stories of the East-vikings. Augsburg publishing house. p. 173. Archived from the original on 17 April 2023. Retrieved 30 January 2023.
Pavel Kokovtsov, when publishing a Russian translation of the letter in 1932, argued that FRS may refer to Thrace, where the Rus' forces were defeated by the armies of Lecapenus (onlineArchived 6 May 2007 at the Wayback Machine).