Edouard Goursat"s three-volume A Course in Mathematical Analysis remains a classic study and a thorough treatment of the fundamentals of calculus. As an advanced text for students with one year of calculus, it offers an exceptionally lucid exposition. The first volume in this series addresses derivatives and differentials, definite integrals, expansion in series, and applications to geometry; the succeeding volume explores functions of a complex variable and differential equations. This, the third and final volume, examines variation of solutions and partial differential equations of the second order in its first part. The second part investigates integral equations and calculus of variations.Topics related to variations of solutions and partial differential equations of the second order include equations of Monge-Ampère; linear equations in n variables; linear equations of the hyperbolic and elliptic types; and harmonic functions in three variables. Subjects relevant to integral equations and calculus of variations include the solution of integral equations by successive approximations; Fredholm"s equation; the fundamental functions; applications of integral equations; and the calculus of variations. The text concludes with a note on conformal representation by Paul Montel.