Top non-fiction books & how to access them for free

Most of us are used to films being ranked on IMDb, but how do we know which are the most valued books? A while ago I did a search and found a number of partial lists scattered around the internet which I pulled into one and standardised the rankings to produce this top 100 spreadsheet.

So how can folk access the material without cost? Well, the Internet Archive's Open Library offers a service where registered users can borrow books to read and/or listen to for free. Here are the links for the top five science books, which I'd strongly recommend for everyone -

1. Sapiens: A Brief History of Humankind, Yuval Noah Harari

2. Cosmos, Carl Sagan

3. Gödel, Escher, Bach: An Eternal Golden Braid, Douglas R. Hofstadter

4. The Demon-Haunted World: Science as a Candle in the Dark, Carl Sagan

5. The Last Lecture, Randy Pausch

The audio option is quite good, and can be sped up, but please note it is computer-generated. Happy reading/listening! I'll extend the list with the next 5 when I get time...