So I want to get into programming with C# for beginners and want to look for a book to buy and study on the go on my phone. The question I have is would it matter if the books are old, maybe from 2013/14? With unity 5 there doesn’t seem to be any books for it. Does programming change over a couple of years?
Any good eBooks out there for beginners?
Unity’s version of C# harks from the dark ages before the discovery of fire; the dawn of primitive man.
So any book would still be relevant?
I wrote a book about Unity 5 that pretty much just came out: Unity in Action
C# doesn’t change, but the Unity-specific stuff does change a bit.
I meant .net, assuming the OP had a blanket statement going.
I’m a fan of the Complete References series of books, and my C# book covers 4.0. If you’re using it as a way to gain a base of knowledge for Unity programming, then I think it’ll do just fine. I couldn’t tell you the differences in the different versions of the language (I think ‘out’ parameters were new to C# 4.0?) or how that relates to the version implemented by Unity, but if you’re looking to just build an understanding of programming and the C# language, I would think any version of the language would work.
The C# Yellow Book is free and quite popular. It is aimed solely at C# though so it doesn’t cover Unity at all.
I keep trying to find that for posting in other threads when people are asking how to learn C#, and I can never remember what it’s called or where it’s located. 
Hmm thanks everyone! I will continue to look around!
I recommend this book also, not C# related or directly related to Unity . But highly value read for any developer.
Design patterns
Any generic programming book will get you the basics. Variables, branches and loops haven’t changed much since programming was invented. I learned programming from a book that had a section on how to use a mouse to point and click.
You will want to learn a bit about OOP, while its been around a long time its become more popular in recent decades. So maybe not quite any book on programming.
As to Unity itself, even the Unity docs are sometimes out of date with the speed the engine is changing. I would recommend against any Unity specific book. Learn programming and game design in general from books, but stick to the docs and forums and actual doing for Unity related stuff.