Kupets, L. A. “The Antique Theme in Music of the Composers of the Nordic Countries (E. Grieg, J. Sibelius, D. Monrad Johansen)”. Music Scholarship / Problemy Muzykal’noj Nauki, vol. 8, no. 1, Apr. 2011, pp. 181-5, https://musicscholar.ru/index.php/PMN/article/view/484.