1. Tritium entry in Wikipedia; https://ru.wikipedia.org/wiki/Тритий (current as of May 2019) (in Russian).
2. V. M. KUZNETSOV and A. G. NAZAROV, The Radioactive Heritage of the Cold War, p. 470, Klyuch-S Publishing, Moscow (2006).
3. Federal State Unitary Enterprise Production Association Mayak Enterprise of the State Rosatom website; https://www.po-mayak.ru (current as of Apr. 14, 2019).
4. Tritium Activities in Russia