Malatsai, L. V. “Russian Soul of the ‘Heavenly Cappella’ (on Spiritual Concerts of A. V. Nikolsky)”. Music Scholarship / Problemy Muzykal’noj Nauki, vol. 6, no. 1, Mar. 2010, pp. 31-36, https://musicscholar.ru/index.php/PMN/article/view/594.