Lectures on Theoretical Physics
Lectures on Theoretical Physics is a six-volume series of physics textbooks translated from Arnold Sommerfeld's classic German texts Vorlesungen über Theoretische Physik. The series includes the volumes Mechanics, Mechanics of Deformable Bodies, Electrodynamics, Optics, Thermodynamics and Statistical Mechanics, and Partial Differential Equations in Physics.
Source: Wikipedia — Lectures on Theoretical Physics (CC BY-SA 4.0)