V. N. Davletshina, “Self-Adjoint Commuting Differential Operators of Rank 2 and Their Deformations Given by Soliton Equations”, Mat. Zametki, 97:3 (2015), 350–358; Math. Notes, 97:3 (2015), 333–340
V. N. Davletshina, E. I. Shamaev, “On commuting differential operators of rank $2$”, Sibirsk. Mat. Zh., 55:4 (2014), 744–749; Siberian Math. J., 55:4 (2014), 606–610