The first book is one Einstein himself wrote to explain relativity to a general audience. There are some good versions of this on Project Gutenberg. Links below.

Here's how Einstein described this book:

> The present book is intended, as far as possible, to give an exact insight into the theory of Relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics. The work presumes a standard of education corresponding to that of a university matriculation examination , and, despite the shortness of the book, a fair amount of patience and force of will on the part of the reader. The author has spared himself no pains in his endeavour to present the main ideas in the simplest and most intelligible form, and on the whole, in the sequence and connection in which they actually originated. In the interest of clearness, it appeared to me inevitable that I should repeat myself frequently, without paying the slightest attention to the elegance of the presentation. I adhered scrupulously to the precept of that brilliant theoretical physicist L. Boltzmann, according to whom matters of elegance ought to be left to the tailor and to the cobbler. I make no pretence of having withheld from the reader difficulties which are inherent to the subject. On the other hand, I have purposely treated the empirical physical foundations of the theory in a "step-motherly" fashion, so that readers unfamiliar with physics may not feel like the wanderer who was unable to see the forest for the trees. May the book bring some one a few happy hours of suggestive thought!

The book is called "Relativity: The Special and the General Theory".

Here is a copy of the 3rd edition in PDF and TeX made via OCR of the physical book [1].

Here is a copy that is available in HTML, MS Word, and TeX. I'm not sure what edition this is [2].

There's also a Kindle version of the 3rd edition on Amazon for $0.99 that is good. Books with math are often terrible on Kindle due to publishers sometimes doing the equations as small image files that are hard to read and ugly if you zoom them. This one, though, is specifically touted as being "with readable equations", and they are right.

Unless you actually want to read on a Kindle there is no advantage that I can see that it has over either of the Gutenberg copies I listed above. If you do want to read on a Kindle and are willing to cough up $0.99, here is the link [3].

Another book that goes over special and general relativity, in a way similar to what I gave in the prior comment (much of mine was ripped off from this, with my contribution just the probably introduction of errors) is Brian Greene's "The Elegant Universe" [4]. I grabbed this when it was free on Amazon Prime Reading a few months ago, and just recently started it. I'm only about 15% of the way through, but it has been quite good so far. The relativity material is only in the first couple of chapters, though, so if you aren't interested in the rest of the material it would probably not be worth it.

[1] http://www.gutenberg.org/ebooks/36114

[2] http://www.gutenberg.org/ebooks/5001

[3] https://www.amazon.com/gp/product/B004M8S53U

[4] https://www.amazon.com/Elegant-Universe-Superstrings-Dimensi...