An Approximation Theory for Generalized Fredholm Quadratic Forms and Integral-Differential Equations

J. Gregory, G. C. Lopez
1976 Transactions of the American Mathematical Society  
An approximation theory is given for a very general class of elliptic quadratic forms which includes the study of 2nth order (usually in integrated form), selfadjoint, integral-differential equations. These ideas follows in
doi:10.2307/1997673 fatcat:pial5ka555dfnjfvtuey5xloeq