Chapter 1. Introduction: Solving the General Quadratic Congruence Modulo a Prime.- Chapter 2. Basic Facts.- Chapter 3. Gauss' Theorema Aureum: the Law of Quadratic Reciprocity.- Chapter 4. Four Interesting Applications of Quadratic Reciprocity.- Chapter 5. The Zeta Function of an Algebraic Number Field and Some Applications.- Chapter 6. Elementary Proofs.- Chapter 7. Dirichlet L-functions and the Distribution of Quadratic Residues.- Chapter 8. Dirichlet's...