Weak formulation of singular differential expressions in spaces of functions with minimal derivatives. El-Gebeily, M.A. (2005) Abstract and Applied Analysis
Weighted estimates for differential operators with operator-valued coefficients W.O. Amrein, A. M. Boutet de Monvel-Berthier, V. Georgescu (1987) Bulletin de la Société Mathématique de France
Weighted inequalities and spectral problems. Kufner, A. (2010) Banach Journal of Mathematical Analysis [electronic only]