Goodreads
Instructions for extracting lists of books by authors from Goodreads
Webometric Analyst can be downloaded free from teh Download link above. It only works on Windows computers, so you may need to borrow a Windows PC or laptop for this.
To extract Goodreads statistics for a list of authors, first find the author home page URLs on Goodreads and store them all in a plain text file, one per line. Next start Webometric Analyst and from the "Services" menu, select the "Goodreads" submenu and the "Download all books by all authors from a list of their Goodreads URLs" sub-submenu option. When prompted, select your plain text file list of authors and wait for Webometric Analyst to finish getting the book information. This may take days if you have a long list of popular authors, but it should not normally take more than an hour.
The results will be in plain text files that you can load into Excel.
WARNING: When Goodreads redesigns its website then this function will stop working altogether without warning, sorry. Please try it with a few URLs to make sure it is working first.