These have been around for a while but I find most either don’t use them or are not aware of them.
An account is required but there are newly released books daily. Most show up again but it takes a while to cycle through with most aging out and newer versions appearing. Good technical references with a few titles listed below for reference.
MongoDB Cookbook - Second Edition
RASPBERRY PI USING PYTHON COOKBOOK
Practical Web Development
Web Development with Django Cookbook - Second Edition
Android 5 Programming by Example
Just figured this could be useful for someone looking for reference material, the material can be downloaded in various formats to include: PDF, ePub, Mobi, Code Files, or just be read online.
A bit more technical in terms of material being to the point. Once again, a few titles listed below for reference.
.NET Framework Notes for Professionals book
C# Notes for Professionals book
MATLAB® Notes for Professionals book
This site is all PDF’s but it’s great since the material has in depth indexes with each section providing code samples. say wahhhh!