Ciereszko, A., A. Kowalczyk, E. Lukaszewicz, A. Krzywinski, A. Kobus, and G. J. Dietrich. “Sperm Characteristics of Male Hybrid from a Cross Between Male Black Grouse Tetrao Tetrix and Female Capercaillie T. Urogallus”. Ornis Fennica, vol. 86, no. 4, Dec. 2009, pp. 149–152, https://ornisfennica.journal.fi/article/view/133736.