Originally Posted by theducks
You might check here (first) in our own MR Library
I agree that if there is a MR version, it is often the best available.
I had not been a fan of Calibre's general Get Books capability, because I found it produces too many hits for simple searches.
However, both the Project Guttenberg and the MobileRead "Store" interfaces work very well, even though they are entirely different. It helps if you click on the binoculars for advanced search.
The all sites search does work better if you select an ebook for an existing author in your library and "Search for this author".