Singular Asymptotic Expansions and Delta Waves for Burger's Equation. T. Gramchev; L. Cadeddu — 1998 Monatshefte für Mathematik
Perturbative methods in scales of Banach spaces: applications for Gevrey regularity of solutions to semilinear partial differential equations. Gramchev, T. — 2003 Rendiconti del Seminario Matematico