1.- I Hilbert Spaces.- II Bounded Linear Operators on a Hilbert Space.- III Unbounded Linear Operators on a Hilbert Space.- 2.- IV Regular Linear Hamiltonian Systems.- V Atkinson's Theory for Singular Hamiltonian Systems of Even Dimension.- VI The Niessen Approach to Singular Hamiltonian Systems.- VII Hinton and Shaw's Extension of Weyl's M(?) Theory to Systems.- VIII Hinton and Shaw's Extension with Two Singular Points.- IX The M (?) Surface.- X The Spectral Resolution for Linear Hamiltonian Systems with One Singular Point.- XI The Spectral Resolution for Linear Hamiltonian Systems with Two Singular Points.- XII Distributions.- 3.- XIII Orthogonal Polynomials.- XIV Orthogonal Polynomials Satisfying Second Order Differential Equations.- XV Orthogonal Polynomials Satisfying Fourth Order Differential Equations.- XVI Orthogonal Polynomials Satisfying Sixth Order Differential Equations.- XVII Orthogonal Polynomials Satisfying Higher Order Differential Equations.- XVIII Differential Operators in Sobolev Spaces.- XIX Examples of Sobolev Differential Operators.- XX The Legendre-Type Polynomials and the Laguerre-Type Polynomials in a Sobolev Spaces.- Closing Remarks.