La teoria de supercuerdas
  We discuss superstring theory based on the reader's intuition and her college knowledge of general physics and calculus. Nowadays, superstring theory is considered the best candidate to explain physical phenomena that involve all of the known fundamental interactions: the gravitational, electromagnetic, weak and strong forces. The main purpose of this work is to show and explain some of the concepts and details about superstrings, such as supersymmetry, compactification, dualities and branes. 
Herbert Morales
physics.pop-ph hep-th