Warning, bad Esperanto translations on Amazon.
If you are going to Amazon to find reading material in Esperanto, buyer beware. Always check the "Look Inside" feature to see the quality of the translation.
There is a recent glut of paperback and electronic edition books in Esperanto introduced on Amazon, IMHO due to the sudden popularity of the language here on Duolingo and in the news. Many of these new books would not be good for beginners.
These new Esperanto Editions on Amazon seem to fall into two catagories.
Printed editions of Esperanto books on Gutenberg.org. These would be great if they would just do a little editing, just simple things like a global search and replace of the x-metodo characters with the real accented characters would make them worth printing and buying.
Electronic translations of un-copyrighted materials. These appear to be works from Gutenberg.org, quickly run through Google Translate then printed without editing. The sad thing is that in some cases, the books have already been human-translated into Esperanto, so better editions already exist.
Buying from an Esperanto organization in your country or region is a much safer bet. The quality of the material there is much better, not that there is not good Esperanto material on Amazon, just that there is a lot of bad stuff too.
This is actually true for every language, not just Esperanto. If you see a public domain or a self-published book in several languages, most likely they've just ran them through Google Translate.
One exception to the self-published recommendation is Tim Westover (www.timwestover.com). His book, Marvirinstrato, is written excellently in Esperanto. I read it a few years back during my first attempt at the language and it helped my proficiency no end. IIRC it's a free download in epub format. The book itself though is not the usual fare being a collection of fairy-tales so probably not for everyone.
Also if you should be unlucky enough to purchase such a book it would be prudent to leave a bad review to spare others the same fate! Thankfully, Amazon is actually really good with their refunds, same with paypal. Very buyer friendly.
Ron103257 is absolutely correct! There are many bad "Esperanto" editions on Amazon for sale.
Many of these bad translations are "translated" by "Onyx Translations," so if you see "Onyx" anywhere on the sale listing page, don't buy it! They fall squarely into Ron103257's category 2. The Onyx translations tend to have beautiful covers, making you think they are high-quality books, when in fact they are not proper translations.
Ironically, some of the books with ugly covers tend to be pretty good (for example, "The Wizard of Oz" at https://www.amazon.com/Mirinda-Sor-%C3%ABisto-Oz-Esperanto/dp/B003YOST02 -- note that they even botched the "ĉ" on the cover). Their main flaw is that they use "cx" together with "ĉ", but other than that, their written content is acceptable. These tend to fall into Ron103257's category 1.
If you're in doubt whether to buy an Esperanto book from Amazon, read the reviews. There usually aren't many, but if any mention that the translation is no good, or seems machine-translated, don't buy the book. You can generally trust the negative reviews.
And by all means, stay away from Onyx Translations. The only positive reviews I've ever read about their books were from people who received a book as a gift, but haven't gotten around to reading it.
I had the same problem with Onyx translations but for Modern Greek. They use a very bad automatic translator-by the way there is no name of human translator of course. I wanted to give a feed back at Amazon.com to avoid further victims but they seem to have luckily completely removed the series.