BKK87 = M.V. Bokhovko, L.E. Kazakov, V.N. Kononov, E.D. Poletaev, V.M. Timokhov, A.A. Voevodskij, Yadernaya Fizika, Vol.46, Issue.1, p.51 (1987); Soviet Journal of Nuclear Physics, Vol.46, Issue.1, p.33 (1987).