A note on higher monotonicity properties of generalized Airy functions Miloš Háčik, Peter Ivan (1984) Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica
Analogies between differential equations: Singular solutions of difference equations of Clairaut's type. J.D. Keckic (1977) Publications de l'Institut Mathématique [Elektronische Ressource]