Python Essential Reference (4th Edition) by David M. Beazley

Python Essential Reference is the definitive reference guide to the Python programming language ― the one authoritative handbook that reliably untangles and explains both the core Python language and the most essential parts of the Python library. Designed for the practicing programmer, the book is concise, to the point, and highly accessible. It also includes detailed information on the Python library and many advanced subjects that is not available in either the official Python documentation or any other single reference source.