Let’s be realistic. A new print copy of Introduccion a la Psicologia can cost $150–$200 USD. However, the phrase "pdf better" implies you want a digital solution. Here is the ethical, cost-effective route to the experience:

Most academic libraries carry physical and digital (Ebook) versions. Google Scholar:

: Clasificación de psicopatologías y sus respectivos enfoques terapéuticos. Características Distintivas