You are a beginner, or you need many solved examples, or you want a heavy emphasis on special relativity and modern applications.
Here’s a concise, critical review of Fundamentos de la Teoría Electromagnética (English: Foundations of Electromagnetic Theory ) by John R. Reitz, Frederick J. Milford, and Robert W. Christy. Target Audience: Advanced undergraduate students (3rd/4th year) in physics or electrical engineering.
Use Griffiths as your primary learning text, but keep Reitz & Milford as an outstanding reference for boundary value problems, macroscopic media, and detailed derivations. In Spanish, it remains one of the most solid intermediate EM textbooks available – just be prepared for a steep climb.
