https://sgp.fas.org/crs/natsec/RL33110.pdf
https://vuosikirja.supo.fi/documents/62399122/66519032/SUPO+Yearbook+2022.pdf/109369e6-13c3-ee60-474e-eff9c4d44217/SUPO+Yearbook+2022.pdf?t=1679642311270
https://www.osce.org/library/14127?download=true
https://www.crisisgroup.org/europe-central-asia/eastern-europe/ukraine/b96-answering-four-hard-questions-about-russias-war-ukraine