R. F. Shamoyan, “On some extremal problems in certain harmonic function spaces of several variables related to mixed norm spaces”, Probl. anal. Issues Anal., 2(20):1 (2013), 43–58
Miloš Arsenović, Romi F. Shamoyan, “Sharp theorems on multipliers and distances in harmonic function spaces in higher dimension”, Zhurn. SFU. Ser. Matem. i fiz., 5:3 (2012), 291–302