Fluent Python: good coverage of idiomatic Python style
http://www.amazon.com/Fluent-Python-Luciano-Ramalho/dp/1491946008

Data Science from Scratch: First Principles with Python
http://www.amazon.com/Data-Science-Scratch-Principles-Python/dp/149190142X

Python Cookbook
http://www.amazon.com/Python-Cookbook-Third-David-Beazley/dp/1449340377

TCP/IP Illustrated, Vol. 1 by W. Richard Stevens: the definitive explanation of how networking works. Try to get the 1st edition. The 2nd edition has mixed reviews on Amazon, and the basic concepts involved are timeless.
http://www.amazon.com/TCP-Illustrated-Vol-Addison-Wesley-Professional/dp/0201633469/ref=sr_1_3?s=books&ie=UTF8&qid=1446163327&sr=1-3